OpenGL_JS-iblIrradiance

Reflection equation

The simplified equation

Diffuse reflection partial equation

P in the center of the environment map only depends on the wi integral
Result: Map the environment cube and its generated irradiance map
Irradiance map: Sample the cube map with any of the vectors to obtain the irradiance of the scene in that direction.

HDR is converted to a floating point number group

Stb_image. h file in learnOpengl, get HDR array directly
- Each channel is 32 bits and each color has 3 channels.
The HDR array is obtained directly from the isometric columnar projection
- Poor performance
- LoadHDR,rgbeToFloat in code
- Each channel is 32 bits and each color has 3 channels.

Go through the cube and then get the six face map

CubeMap vertex shader

export var vs_cubemap =
`#version 300 es
precision mediump float;
layout (location = 0) in vec3 aPos;
out vec3 WorldPos;
uniform mat4 projection;
uniform mat4 view;
void main()
{
    WorldPos = aPos;  
    gl_Position =  projection * view * vec4(WorldPos, 1.0); } `Copy the code

CubeMap slice shader

export var fs_equirectangularToCubemap =
`#version 300 es
precision mediump float;
out vec4 FragColor;
//out uvec4 uFragColor;
in vec3 WorldPos;
uniform sampler2D equirectangularMap;
//conversion from (-pi, pi)=>(-1/2, 1/2) and (-pi/2, pi/2)=>(-1/2, 1/2) 
const vec2 invAtan = vec2(0.1591.0.3183);
vec2 SampleSphericalMap(vec3 v)
{
    vec2 uv = vec2(atan(v.z, v.x), asin(v.y));
    uv *= invAtan;
    uv += 0.5;
    return uv;
}
void main()
{		
    vec2 uv = SampleSphericalMap(normalize(WorldPos));
    vec3 color = texture(equirectangularMap, uv).rgb;
    FragColor = vec4(color, 1.0);
    //uFragColor = uvec4(100, 0, 0, 1);} `Copy the code

FBO generates envCubemap cube maps

captureFBO = gl.createFramebuffer();
let captureRBO = gl.createRenderbuffer();
gl.bindFramebuffer(gl.FRAMEBUFFER, captureFBO);
gl.bindRenderbuffer(gl.RENDERBUFFER, captureRBO);
gl.renderbufferStorage(gl.RENDERBUFFER, gl.DEPTH_COMPONENT24, whCube, whCube);
gl.framebufferRenderbuffer(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.RENDERBUFFER, captureRBO);
//----------------------------------------
//createTexture bindTexture texImage2D
envCubemap = gl.createTexture();
gl.bindTexture(gl.TEXTURE_CUBE_MAP, envCubemap);
for (let i = 0; i < 6; ++i) {
    gl.texImage2D(gl.TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, gl.RGBA16F, whCube, whCube, 0, gl.RGBA, gl.FLOAT, new Float32Array(whCube * whCube * 4));
}
gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_WRAP_R, gl.CLAMP_TO_EDGE);
gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
let captureProjection = mat4.create();
mat4.perspective(captureProjection, (90.0) * Math.PI / 180.1.0.0.1.10.0);
equirectangularToCubemapShader.use(gl);
equirectangularToCubemapShader.setInt(gl, "equirectangularMap".0);
gl.uniformMatrix4fv(gl.getUniformLocation(equirectangularToCubemapShader.programId, "projection"), false, captureProjection);
gl.activeTexture(gl.TEXTURE0);
gl.bindTexture(gl.TEXTURE_2D, hdrTexture);
gl.viewport(0.0, whCube, whCube);
gl.bindFramebuffer(gl.FRAMEBUFFER, captureFBO);
let captureViews = [
    mat4.lookAt(mat4.create(), vec3.fromValues(0.0.0.0.0.0), vec3.fromValues(1.0.0.0.0.0), vec3.fromValues(0.0, -1.0.0.0)),
    mat4.lookAt(mat4.create(), vec3.fromValues(0.0.0.0.0.0), vec3.fromValues(-1.0.0.0.0.0), vec3.fromValues(0.0, -1.0.0.0)),
    mat4.lookAt(mat4.create(), vec3.fromValues(0.0.0.0.0.0), vec3.fromValues(0.0.1.0.0.0), vec3.fromValues(0.0.0.0.1.0)),
    mat4.lookAt(mat4.create(), vec3.fromValues(0.0.0.0.0.0), vec3.fromValues(0.0, -1.0.0.0), vec3.fromValues(0.0.0.0, -1.0)),
    mat4.lookAt(mat4.create(), vec3.fromValues(0.0.0.0.0.0), vec3.fromValues(0.0.0.0.1.0), vec3.fromValues(0.0, -1.0.0.0)),
    mat4.lookAt(mat4.create(), vec3.fromValues(0.0.0.0.0.0), vec3.fromValues(0.0.0.0, -1.0), vec3.fromValues(0.0, -1.0.0.0))];for (let i = 0; i < 6; ++i) {
    gl.uniformMatrix4fv(gl.getUniformLocation(equirectangularToCubemapShader.programId, "view"), false, captureViews[i]);
    gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_CUBE_MAP_POSITIVE_X + i, envCubemap, 0);
    gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
    renderCube(); // renders a 1x1 cube
}
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Display the cube bounding box

Background vertex shader

export var vs_background =
`#version 300 es
precision mediump float;
layout (location = 0) in vec3 aPos;
uniform mat4 projection;
uniform mat4 view;
out vec3 WorldPos;
void main()
{
    WorldPos = aPos;
    mat4 rotView = mat4(mat3(view));
    vec4 clipPos = projection * rotView * vec4(WorldPos, 1.0);
    // Note the trick here xyww ensures that rendered cube segments always have a depth value of 1.0, the maximum depth, as described in the cube mapping tutorial. Note that we need to change the depth comparison function to GL_LEQUAL:
    //glDepthFunc(GL_LEQUAL);  
    gl_Position= clipPos.xyww; } `Copy the code

Background slice shader

export var fs_background =
`#version 300 es
precision mediump float;
out vec4 FragColor;
in vec3 WorldPos;
uniform samplerCube environmentMap;
void main()
{		
    vec3 envColor = texture(environmentMap, WorldPos).rgb;
    // HDR tonemap and gamma correct
    envColor = envColor / (envColor + vec3(1.0));
    envColor = pow(envColor, vec3(1.0/2.2)); 
    FragColor = vec4(envColor, 1.0); } `Copy the code

The cube map shows the cube bounding box

backgroundShader.use(gl);
gl.uniformMatrix4fv(gl.getUniformLocation(backgroundShader.programId, "view"), false, view);
gl.activeTexture(gl.TEXTURE0);
if (showCubeMap)
    gl.bindTexture(gl.TEXTURE_CUBE_MAP, envCubemap);
else
    gl.bindTexture(gl.TEXTURE_CUBE_MAP, irradianceMap);
renderCube();
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The convolution of the cube map

Convolving the cube map is equivalent to calculating the total average emissivity of WI in each direction of hemispheric OMEGA towards N.
CubeMap vertex shader

export var vs_cubemap =
`#version 300 es
precision mediump float;
layout (location = 0) in vec3 aPos;

out vec3 WorldPos;

uniform mat4 projection;
uniform mat4 view;

void main()
{
    WorldPos = aPos;  
    gl_Position =  projection * view * vec4(WorldPos, 1.0); } `Copy the code

IrradianceConvolution Slice shader

export var fs_irradianceConvolution =
`#version 300 es
precision mediump float;
out vec4 FragColor;
in vec3 WorldPos;
uniform samplerCube environmentMap;
const float PI = 3.14159265359;
void main()
{		
	// The world vector acts as the normal of a tangent surface
    // from the origin, aligned to WorldPos. Given this normal, calculate all
    // incoming radiance of the environment. The result of this radiance
    // is the radiance of light coming from -Normal direction, which is what
    // we use in the PBR shader to sample irradiance.
    vec3 N = normalize(WorldPos);
    vec3 irradiance = vec3(0.0);   
    // tangent space calculation from origin point
    vec3 up    = vec3(0.0.1.0.0.0);
    vec3 right = cross(up, N);
    up            = cross(N, right);
    float sampleDelta = 0.025; // We traverse the hemisphere with a fixed sampleDelta increment. Decreasing (or increasing) this increment will increase (or decrease) accuracy.
    float nrSamples = 0.0;
    for(float phi = 0.0; phi < 2.0 * PI; phi += sampleDelta)
    {
        for(float theta = 0.0; theta < 0.5 * PI; theta += sampleDelta)
        {
            // spherical to cartesian (in tangent space)
            vec3 tangentSample = vec3(sin(theta) * cos(phi),  sin(theta) * sin(phi), cos(theta));
            // tangent space to world
            vec3 sampleVec = tangentSample.x * right + tangentSample.y * up + tangentSample.z * N; 
            irradiance += texture(environmentMap, sampleVec).rgb * cos(theta) * sin(theta);
            nrSamples++;
        }
    }
    irradiance = PI * irradiance * (1.0 / float(nrSamples));
    FragColor = vec4(irradiance, 1.0); } `Copy the code

FBO gets the convolution of the cube map irradianceMap

gl.bindFramebuffer(gl.FRAMEBUFFER, null);
const whIrradiance = 32; // Lower resolution (32x32) storage
irradianceMap = gl.createTexture();
gl.bindTexture(gl.TEXTURE_CUBE_MAP, irradianceMap);
for (let i = 0; i < 6; ++i) {
    gl.texImage2D(gl.TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, gl.RGBA16F, whIrradiance, whIrradiance, 0, gl.RGBA, gl.FLOAT, new Float32Array(whIrradiance * whIrradiance * 4));
}
gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_WRAP_R, gl.CLAMP_TO_EDGE);
gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
//----------------------------------------
// bindFramebuffer bindRenderbuffer renderbufferStorage
gl.bindFramebuffer(gl.FRAMEBUFFER, captureFBO);
gl.bindRenderbuffer(gl.RENDERBUFFER, captureRBO);
gl.renderbufferStorage(gl.RENDERBUFFER, gl.DEPTH_COMPONENT24, whIrradiance, whIrradiance);
irradianceShader.use(gl);
irradianceShader.setInt(gl, "environmentMap".0);
gl.uniformMatrix4fv(gl.getUniformLocation(irradianceShader.programId, "projection"), false, captureProjection);
gl.activeTexture(gl.TEXTURE0);
gl.bindTexture(gl.TEXTURE_CUBE_MAP, envCubemap);
gl.viewport(0.0, whIrradiance, whIrradiance); // don't forget to configure the viewport to the capture dimensions.
gl.bindFramebuffer(gl.FRAMEBUFFER, captureFBO);
for (let i = 0; i < 6; ++i) {
    gl.uniformMatrix4fv(gl.getUniformLocation(irradianceShader.programId, "view"), false, captureViews[i]);
    gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_CUBE_MAP_POSITIVE_X + i, irradianceMap, 0);
    gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
    renderCube();
}
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PBR and indirect irradiance illumination

PBR vertex shader

export var vs_pbr =
`#version 300 es
precision mediump float;
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec2 aTexCoords;
layout (location = 2) in vec3 aNormal;
out vec2 TexCoords;
out vec3 WorldPos;
out vec3 Normal;
uniform mat4 projection;
uniform mat4 view;
uniform mat4 model;
void main()
{
    TexCoords = aTexCoords;
    WorldPos = vec3(model * vec4(aPos, 1.0));
    Normal = mat3(model) * aNormal;   
    gl_Position =  projection * view * vec4(WorldPos, 1.0); } `Copy the code

PBR chip shader

export var fs_pbr =
`#version 300 es
precision mediump float;
out vec4 FragColor;
in vec2 TexCoords;
in vec3 WorldPos;
in vec3 Normal;
// material parameters
uniform vec3 albedo;
uniform float metallic;
uniform float roughness;
uniform float ao;
// IBL
uniform samplerCube irradianceMap; // The updated part
// lights
uniform vec3 lightPositions[4];
uniform vec3 lightColors[4];
uniform vec3 camPos;
const float PI = 3.14159265359;
// ----------------------------------------------------------------------------
float DistributionGGX(vec3 N, vec3 H, float roughness)
{
    float a = roughness*roughness;
    float a2 = a*a;
    float NdotH = max(dot(N, H), 0.0);
    float NdotH2 = NdotH*NdotH;

    float nom   = a2;
    float denom = (NdotH2 * (a2 - 1.0) + 1.0);
    denom = PI * denom * denom;
    return nom / denom;
}
// ----------------------------------------------------------------------------
float GeometrySchlickGGX(float NdotV, float roughness)
{
    float r = (roughness + 1.0);
    float k = (r*r) / 8.0;
    float nom   = NdotV;
    float denom = NdotV * (1.0 - k) + k;
    return nom / denom;
}
// ----------------------------------------------------------------------------
float GeometrySmith(vec3 N, vec3 V, vec3 L, float roughness)
{
    float NdotV = max(dot(N, V), 0.0);
    float NdotL = max(dot(N, L), 0.0);
    float ggx2 = GeometrySchlickGGX(NdotV, roughness);
    float ggx1 = GeometrySchlickGGX(NdotL, roughness);
    return ggx1 * ggx2;
}
// ----------------------------------------------------------------------------
vec3 fresnelSchlick(float cosTheta, vec3 F0)
{
    return F0 + (1.0 - F0) * pow(1.0 - cosTheta, 5.0);
}
vec3 fresnelSchlickRoughness(float cosTheta, vec3 F0, float roughness)
{
    return F0 + (max(vec3(1.0 - roughness), F0) - F0) * pow(1.0 - cosTheta, 5.0);
}   
// ----------------------------------------------------------------------------
void main()
{		
    vec3 N = Normal;
    vec3 V = normalize(camPos - WorldPos);
    vec3 R = reflect(-V, N); 
    // calculate reflectance at normal incidence; if dia-electric (like plastic) use F0 
    // of 0.04 and if it's a metal, use the albedo color as F0 (metallic workflow)    
    vec3 F0 = vec3(0.04); 
    F0 = mix(F0, albedo, metallic);
    // reflectance equation
    vec3 Lo = vec3(0.0);
    for(int i = 0; i < 4; ++i) 
    {
        // calculate per-light radiance
        vec3 L = normalize(lightPositions[i] - WorldPos);
        vec3 H = normalize(V + L);
        float distance = length(lightPositions[i] - WorldPos);
        float attenuation = 1.0 / (distance * distance);
        vec3 radiance = lightColors[i] * attenuation;
        // Cook-Torrance BRDF
        float NDF = DistributionGGX(N, H, roughness);   
        float G   = GeometrySmith(N, V, L, roughness);    
        vec3 F    = fresnelSchlick(max(dot(H, V), 0.0), F0);        
        vec3 nominator    = NDF * G * F;
        float denominator = 4.0 * max(dot(N, V), 0.0) * max(dot(N, L), 0.0) + 0.001; // 0.001 to prevent divide by zero.
        vec3 specular = nominator / denominator;
         // kS is equal to Fresnel
        vec3 kS = F;
        // for energy conservation, the diffuse and specular light can't
        // be above 1.0 (unless the surface emits light); to preserve this
        // Relationship the diffuse Component (kD) should equal 1.0-ks.
        vec3 kD = vec3(1.0) - kS;
        // multiply kD by the inverse metalness such that only non-metals 
        // have diffuse lighting, or a linear blend if partly metal (pure metals
        // have no diffuse light).
        kD *= 1.0 - metallic;	                
        // scale light by NdotL
        float NdotL = max(dot(N, L), 0.0);        
        // add to outgoing radiance Lo
        Lo += (kD * albedo / PI + specular) * radiance * NdotL; // note that we already multiplied the BRDF by the Fresnel (kS) so we won't multiply by kS again
    }   
    // ambient lighting (we now use IBL as the ambient term)
    vec3 kS = fresnelSchlick(max(dot(N, V), 0.0), F0);
    vec3 kD = 1.0 - kS;
    kD *= 1.0 - metallic;	  
    vec3 irradiance = texture(irradianceMap, N).rgb;
    vec3 diffuse      = irradiance * albedo; / / multiplied
    vec3 ambient = (kD * diffuse) * ao; / / multiplied
    // ambient = vec3(0.002);
    vec3 color = ambient + Lo;
    // HDR tonemapping
    color = color / (color + vec3(1.0));
    // gamma correct
    color = pow(color, vec3(1.0/2.2)); 
    FragColor = vec4(color , 1.0); } `Copy the code

Shader runs on the sphere

let currentFrame = performance.now();
deltaTime = currentFrame - lastFrame;
lastFrame = currentFrame;
processInput();
gl.clearColor(0.1.0.1.0.1.1.0);
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
pbrShader.use(gl);
view = camera.GetViewMatrix();
gl.uniformMatrix4fv(gl.getUniformLocation(pbrShader.programId, "view"), false, view);
gl.uniform3fv(gl.getUniformLocation(pbrShader.programId, "camPos"), new Float32Array(camera.Position));
gl.activeTexture(gl.TEXTURE0);
gl.bindTexture(gl.TEXTURE_CUBE_MAP, irradianceMap);
mat4.identity(model);
for (let row = 0; row < nrRows; ++row) {
    pbrShader.setFloat(gl, "metallic", row / nrRows);
    for (let col = 0; col < nrColumns; ++col) {
        pbrShader.setFloat(gl, "roughness".Math.min(Math.max(col / nrColumns, 0.025), 1.0));
        mat4.identity(model);
        mat4.translate(model, model, vec3.fromValues((col - (nrColumns / 2)) * spacing, (row - (nrRows / 2)) * spacing, 0.0));
        gl.uniformMatrix4fv(gl.getUniformLocation(pbrShader.programId, "model"), false, model); renderSphere2(); }}for (let i = 0; i < lightPositions.length / 3; ++i) {
    let newPos = vec3.fromValues(lightPositions[3 * i], lightPositions[3 * i + 1], lightPositions[3 * i + 2]);
    pbrShader.setFloat(gl, "metallic".1.0);
    pbrShader.setFloat(gl, "roughness".1.0);
    mat4.identity(model);
    mat4.translate(model, model, newPos);
    mat4.scale(model, model, vec3.fromValues(0.5.0.5.0.5));
    gl.uniformMatrix4fv(gl.getUniformLocation(pbrShader.programId, "model"), false, model);
    renderSphere2();
    requestAnimationFrame(render);
}
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function renderSphere2() {
    if (sphereVAO == null) {
        sphere = new Sphere2(1.0.14.14.0.2 * Math.PI, 0.Math.PI);
        sphereVAO = gl.createVertexArray();
        let vbo = gl.createBuffer();
        let ebo = gl.createBuffer();
        gl.bindVertexArray(sphereVAO);
        gl.bindBuffer(gl.ARRAY_BUFFER, vbo);
        gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(sphere.vertices), gl.STATIC_DRAW);
        gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, ebo);
        gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint16Array(sphere.indices), gl.STATIC_DRAW);
        let stride = (3 + 2 + 3) * sizeFloat;
        gl.enableVertexAttribArray(0);
        gl.vertexAttribPointer(0.3, gl.FLOAT, false, stride, 0);
        gl.enableVertexAttribArray(1);
        gl.vertexAttribPointer(1.2, gl.FLOAT, false, stride, (3 * sizeFloat));
        gl.enableVertexAttribArray(2);
        gl.vertexAttribPointer(2.3, gl.FLOAT, false, stride, (5 * sizeFloat));
    }
    gl.bindVertexArray(sphereVAO);
    gl.drawElements(gl.TRIANGLE_STRIP, sphere.indexCount, gl.UNSIGNED_SHORT, 0);
}
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code

CubeMap vertex shader

export var vs_cubemap =
`#version 300 es precision mediump float; layout (location = 0) in vec3 aPos; out vec3 WorldPos; uniform mat4 projection; uniform mat4 view; void main() { WorldPos = aPos; Gl_Position = projection * view * VEC4 (WorldPos, 1.0); } `
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CubeMap slice shader

export var fs_equirectangularToCubemap =
`#version 300 es precision mediump float; out vec4 FragColor; //out uvec4 uFragColor; in vec3 WorldPos; uniform sampler2D equirectangularMap; / / conversion from (- PI, PI) = > (1/2) - 1/2, and (PI / 2, PI / 2) = > (1/2) - 1/2, const vec2 invAtan = vec2 (0.1591, 0.3183); vec2 SampleSphericalMap(vec3 v) { vec2 uv = vec2(atan(v.z, v.x), asin(v.y)); uv *= invAtan; Uv + = 0.5; return uv; } void main() { vec2 uv = SampleSphericalMap(normalize(WorldPos)); vec3 color = texture(equirectangularMap, uv).rgb; FragColor = vec4 (color, 1.0); //uFragColor = uvec4(100, 0, 0, 1); } `
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Background vertex shader

export var vs_background =
`#version 300 es precision mediump float; layout (location = 0) in vec3 aPos; uniform mat4 projection; uniform mat4 view; out vec3 WorldPos; void main() { WorldPos = aPos; mat4 rotView = mat4(mat3(view)); Vec4 clipPos = projection * rotView * VEC4 (WorldPos, 1.0); gl_Position = clipPos.xyww; } `
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Background slice shader

export var fs_background =
`#version 300 es precision mediump float; out vec4 FragColor; in vec3 WorldPos; uniform samplerCube environmentMap; void main() { vec3 envColor = texture(environmentMap, WorldPos).rgb; // HDR tonemap and gamma correct envColor = envColor/(envColor + vec3(1.0)); (envColor, vec3 envColor = pow (1.0/2.2)); FragColor = vec4 (envColor, 1.0); } `
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irradianceConvolution

export var fs_irradianceConvolution =
`#version 300 es precision mediump float; out vec4 FragColor; in vec3 WorldPos; uniform samplerCube environmentMap; Const float PI = 3.14159265359; void main() { // The world vector acts as the normal of a tangent surface // from the origin, aligned to WorldPos. Given this normal, calculate all // incoming radiance of the environment. The result of this radiance // is the radiance of light coming from -Normal direction, which is what // we use in the PBR shader to sample irradiance. vec3 N = normalize(WorldPos); Vec3 irradiance = vec3 (0.0); // Tangent space calculation from origin point vec3 up = vec3(0.0, 1.0, 0.0); vec3 right = cross(up, N); up = cross(N, right); Float sampleDelta = 0.025; Float nrSamples = 0.0; For (float phi = 0.0; Phi < 2.0 * PI; Phi += sampleDelta) {for(float theta = 0.0; Theta < 0.5 * PI; theta += sampleDelta) { // spherical to cartesian (in tangent space) vec3 tangentSample = vec3(sin(theta) * cos(phi), sin(theta) * sin(phi), cos(theta)); // tangent space to world vec3 sampleVec = tangentSample.x * right + tangentSample.y * up + tangentSample.z * N; irradiance += texture(environmentMap, sampleVec).rgb * cos(theta) * sin(theta); nrSamples++; Irradiance = PI * IRradiance * (1.0 / float(nrSamples)); FragColor = vec4 (irradiance, 1.0); } `
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PBR vertex shader

export var vs_pbr =
`#version 300 es precision mediump float; layout (location = 0) in vec3 aPos; layout (location = 1) in vec2 aTexCoords; layout (location = 2) in vec3 aNormal; out vec2 TexCoords; out vec3 WorldPos; out vec3 Normal; uniform mat4 projection; uniform mat4 view; uniform mat4 model; void main() { TexCoords = aTexCoords; Vec3 (Model * VEC4 (aPos, 1.0)); Normal = mat3(model) * aNormal; Gl_Position = projection * view * VEC4 (WorldPos, 1.0); } `
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PBR chip shader

export var fs_pbr =
`#version 300 es precision mediump float; out vec4 FragColor; in vec2 TexCoords; in vec3 WorldPos; in vec3 Normal; // material parameters uniform vec3 albedo; uniform float metallic; uniform float roughness; uniform float ao; // IBL uniform samplerCube irradianceMap; // lights uniform vec3 lightPositions[4]; uniform vec3 lightColors[4]; uniform vec3 camPos; Const float PI = 3.14159265359; // ---------------------------------------------------------------------------- float DistributionGGX(vec3 N, vec3 H, float roughness) { float a = roughness*roughness; float a2 = a*a; Float NdotH = Max (dot(N, H), 0.0); float NdotH2 = NdotH*NdotH; float nom = a2; Float denom = (NdotH2 * (a2-1.0) + 1.0); float denom = (NdotH2 * (a2-1.0) + 1.0); denom = PI * denom * denom; return nom / denom; } // ---------------------------------------------------------------------------- float GeometrySchlickGGX(float NdotV, Float roughness) {float r = (roughness + 1.0); Float k = (r*r) / 8.0; float k = (r*r) / 8.0; float nom = NdotV; Float denom = NdotV * (1.0-k) + k; float denom = NdotV * (1.0-k) + k; return nom / denom; } // ---------------------------------------------------------------------------- float GeometrySmith(vec3 N, vec3 V, Vec3 L, float roughness) {float NdotV = Max (dot(N, V), 0.0); Float NdotL = Max (dot(N, L), 0.0); float NdotL = Max (dot(N, L), 0.0); float ggx2 = GeometrySchlickGGX(NdotV, roughness); float ggx1 = GeometrySchlickGGX(NdotL, roughness); return ggx1 * ggx2; } // ---------------------------------------------------------------------------- vec3 fresnelSchlick(float cosTheta, Vec3 F0) {return F0 + (1.0-f0) * pow(1.0-costheta, 5.0); } // ---------------------------------------------------------------------------- void main() { vec3 N = Normal; vec3 V = normalize(camPos - WorldPos); vec3 R = reflect(-V, N); // calculate reflectance at normal incidence; If dia-electric (like plastic) use F0 // of 0.04 and if it's a metal, Use the Albedo color as F0 (metallic Workflow) VEC3 F0 = VEC3 (0.04); F0 = mix(F0, albedo, metallic); // Reflectance equation vec3 Lo = vec3(0.0); for(int i = 0; i < 4; ++i) { // calculate per-light radiance vec3 L = normalize(lightPositions[i] - WorldPos); vec3 H = normalize(V + L); float distance = length(lightPositions[i] - WorldPos); Float elevation = 1.0 / (distance * distance); float elevation = 1.0 / (distance * distance); vec3 radiance = lightColors[i] * attenuation; // Cook-Torrance BRDF float NDF = DistributionGGX(N, H, roughness); float G = GeometrySmith(N, V, L, roughness); Vec3 F = fresnelSchlick(Max (dot(H, V), 0.0), F0); vec3 nominator = NDF * G * F; Float denominator = 4.0 * Max (dot(N, V), 0.0) * Max (dot(N, L), 0.0) + 0.001; Vec3 specular = nominator/free; // kS is equal to Fresnel vec3 kS = F; For energy conservation, the diffuse and specular light can't // be above 1.0 (unless the surface emits light); To preserve this // Relationship the diffuse Component (kD) should equal 1.0-ks. Vec3 kD = vec3(1.0) -ks; // multiply kD by the inverse metalness such that only non-metals // have diffuse lighting, Or a linear blend if partly metal (pure metal // have no diffuse light). KD *= 1.0-metallic; // Scale light by NdotL float NdotL = Max (dot(N, L), 0.0); // add to outgoing radiance Lo Lo += (kD * albedo / PI + specular) * radiance * NdotL; // note that we already multiplied the BRDF by the Fresnel (kS) so we won't multiply by kS again } // ambient lighting (We now use IBL as the ambient term) vec3ks = fresnelSchlick(Max (dot(N, V), 0.0), F0); Vec3 kD = 1.0-ks; KD *= 1.0-metallic; vec3 irradiance = texture(irradianceMap, N).rgb; vec3 diffuse = irradiance * albedo; vec3 ambient = (kD * diffuse) * ao; // ambient = vec3(0.002); vec3 color = ambient + Lo; // HDR tonemapping color = color (color + vec3(1.0)); // gamma correct color = pow(color, vec3(1.0/2.2)); FragColor = vec4(color, 1.0); } `
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code

const sizeFloat = 4;
const whCube = 512;
const ext = gl.getExtension("EXT_color_buffer_float");
let showCubeMap = true;
let spacePressed = false;
let pbrShader = null;
let equirectangularToCubemapShader = null;
let irradianceShader = null;
let backgroundShader = null;
let projection = mat4.create(), view = mat4.create();
let model = mat4.create();
let lightPositions = null;
let lightColors = null;
const nrRows = 7;
const nrColumns = 7;
const spacing = 2.5;
let cubeVAO = null;
let quadVAO = null;
let envCubemap = null;
let sphereVAO = null;
let sphere;
let captureFBO = null;
let irradianceMap = null;
let camera = new Camera(vec3.fromValues(0.0.0.0.5.0), vec3.fromValues(0.0.1.0.0.0));

let main = function () {
    gl.enable(gl.DEPTH_TEST);
    gl.depthFunc(gl.LEQUAL);
    pbrShader = new Shader(gl, vs_pbr, fs_pbr);
    equirectangularToCubemapShader = new Shader(gl, vs_cubemap, fs_equirectangularToCubemap);
    irradianceShader = new Shader(gl, vs_cubemap, fs_irradianceConvolution);
    backgroundShader = new Shader(gl, vs_background, fs_background);
    pbrShader.use(gl);
    pbrShader.setInt(gl, "irradianceMap".0);
    gl.uniform3f(gl.getUniformLocation(pbrShader.programId, "albedo"), 0.5.0.0.0.0);
    pbrShader.setFloat(gl, "ao".1.0);
    backgroundShader.use(gl);
    backgroundShader.setInt(gl, "environmentMap".0);
    lightPositions = new Float32Array([-10.0.10.0.10.0.10.0.10.0.10.0,
        -10.0, -10.0.10.0.10.0, -10.0.10.0
    ]);
    lightColors = new Float32Array([
        300.0.300.0.300.0.300.0.300.0.300.0.300.0.300.0.300.0.300.0.300.0.300.0
    ]);
    loadHDR(".. /.. /textures/hdr/newport_loft.hdr", toCubemap); } ();Copy the code

Render balls of different roughness and metallicity

function render() {
    let currentFrame = performance.now();
    deltaTime = currentFrame - lastFrame;
    lastFrame = currentFrame;
    processInput();
    gl.clearColor(0.1.0.1.0.1.1.0);
    gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
    pbrShader.use(gl);
    view = camera.GetViewMatrix();
    gl.uniformMatrix4fv(gl.getUniformLocation(pbrShader.programId, "view"), false, view);
    gl.uniform3fv(gl.getUniformLocation(pbrShader.programId, "camPos"), new Float32Array(camera.Position));
    gl.activeTexture(gl.TEXTURE0);
    gl.bindTexture(gl.TEXTURE_CUBE_MAP, irradianceMap);
    mat4.identity(model);
    for (let row = 0; row < nrRows; ++row) {
        pbrShader.setFloat(gl, "metallic", row / nrRows);
        for (let col = 0; col < nrColumns; ++col) {
            pbrShader.setFloat(gl, "roughness".Math.min(Math.max(col / nrColumns, 0.025), 1.0));
            mat4.identity(model);
            mat4.translate(model, model, vec3.fromValues((col - (nrColumns / 2)) * spacing, (row - (nrRows / 2)) * spacing, 0.0));
            gl.uniformMatrix4fv(gl.getUniformLocation(pbrShader.programId, "model"), false, model); renderSphere2(); }}for (let i = 0; i < lightPositions.length / 3; ++i) {
        let newPos = vec3.fromValues(lightPositions[3 * i], lightPositions[3 * i + 1], lightPositions[3 * i + 2]);
        pbrShader.setFloat(gl, "metallic".1.0);
        pbrShader.setFloat(gl, "roughness".1.0);
        mat4.identity(model);
        mat4.translate(model, model, newPos);
        mat4.scale(model, model, vec3.fromValues(0.5.0.5.0.5));
        gl.uniformMatrix4fv(gl.getUniformLocation(pbrShader.programId, "model"), false, model);
        renderSphere2();
        requestAnimationFrame(render);
    }
    backgroundShader.use(gl);
    gl.uniformMatrix4fv(gl.getUniformLocation(backgroundShader.programId, "view"), false, view);
    gl.activeTexture(gl.TEXTURE0);
    if (showCubeMap)
        gl.bindTexture(gl.TEXTURE_CUBE_MAP, envCubemap);
    else
        gl.bindTexture(gl.TEXTURE_CUBE_MAP, irradianceMap);
    renderCube();
}
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Load the sphere

function renderSphere2() {
    if (sphereVAO == null) {
        sphere = new Sphere2(1.0.14.14.0.2 * Math.PI, 0.Math.PI);
        sphereVAO = gl.createVertexArray();
        let vbo = gl.createBuffer();
        let ebo = gl.createBuffer();
        gl.bindVertexArray(sphereVAO);
        gl.bindBuffer(gl.ARRAY_BUFFER, vbo);
        gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(sphere.vertices), gl.STATIC_DRAW);
        gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, ebo);
        gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint16Array(sphere.indices), gl.STATIC_DRAW);
        let stride = (3 + 2 + 3) * sizeFloat;
        gl.enableVertexAttribArray(0);
        gl.vertexAttribPointer(0.3, gl.FLOAT, false, stride, 0);
        gl.enableVertexAttribArray(1);
        gl.vertexAttribPointer(1.2, gl.FLOAT, false, stride, (3 * sizeFloat));
        gl.enableVertexAttribArray(2);
        gl.vertexAttribPointer(2.3, gl.FLOAT, false, stride, (5 * sizeFloat));
    }
    gl.bindVertexArray(sphereVAO);
    gl.drawElements(gl.TRIANGLE_STRIP, sphere.indexCount, gl.UNSIGNED_SHORT, 0);
}
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Load the HDR file and call back a function

// Loading HDR completion is the tocubemap function
function loadHDR(url, completion) {
    var req = m(new XMLHttpRequest(), { responseType: "arraybuffer" });
    req.onerror = completion.bind(req, false);
    req.onload = function () {
        if (this.status >= 400)
            return this.onerror();
        var header = ' ', pos = 0, d8 = new Uint8Array(this.response), format;
        while(! header.match(/\n\n[^\n]+\n/g))
            header += String.fromCharCode(d8[pos++]);
        format = header.match(/FORMAT=(.*)$/m) [1];
        if(format ! ='32-bit_rle_rgbe')
            return console.warn('unknown format : ' + format), this.onerror();
        var rez = header.split(/\n/).reverse()[1].split(' '), width = +rez[3] * 1, height = +rez[1] * 1;
        var img = new Uint8Array(width * height * 4), ipos = 0;
        for (var j = 0; j < height; j++) {
            var rgbe = d8.slice(pos, pos += 4), scanline = [];
            if (rgbe[0] != 2 || (rgbe[1] != 2) || (rgbe[2] & 0x80)) {
                var len = width, rs = 0;
                pos -= 4;
                while (len > 0) {
                    img.set(d8.slice(pos, pos += 4), ipos);
                    if (img[ipos] == 1 && img[ipos + 1] = =1 && img[ipos + 2] = =1) {
                        for (img[ipos + 3] << rs; i > 0; i--) {
                            img.set(img.slice(ipos - 4, ipos), ipos);
                            ipos += 4;
                            len--;
                        }
                        rs += 8;
                    }
                    else {
                        len--;
                        ipos += 4;
                        rs = 0; }}}else {
                if ((rgbe[2] < <8) + rgbe[3] != width)
                    return console.warn('HDR line mismatch .. '), this.onerror();
                for (var i = 0; i < 4; i++) {
                    var ptr = i * width, ptr_end = (i + 1) * width, buf, count;
                    while (ptr < ptr_end) {
                        buf = d8.slice(pos, pos += 2);
                        if (buf[0] > 128) {
                            count = buf[0] - 128;
                            while (count-- > 0)
                                scanline[ptr++] = buf[1];
                        }
                        else {
                            count = buf[0] - 1;
                            scanline[ptr++] = buf[1];
                            while (count-- > 0) scanline[ptr++] = d8[pos++]; }}}for (var i = 0; i < width; i++) {
                    img[ipos++] = scanline[i];
                    img[ipos++] = scanline[i + width];
                    img[ipos++] = scanline[i + 2 * width];
                    img[ipos++] = scanline[i + 3 * width];
                }
            }
        }
        completion && completion(img, width, height);
    };
    req.open("GET", url, true);
    req.send(null);
    return req;
}
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After loading the HDR file, the callback function

function toCubemap(data, width, height) {
    //----------------------------------------
    //createFramebuffer bindFramebuffer framebufferRenderbuffer
    //createRenderbuffer bindRenderbuffer renderbufferStorage
    captureFBO = gl.createFramebuffer();
    let captureRBO = gl.createRenderbuffer();
    gl.bindFramebuffer(gl.FRAMEBUFFER, captureFBO);
    gl.bindRenderbuffer(gl.RENDERBUFFER, captureRBO);
    gl.renderbufferStorage(gl.RENDERBUFFER, gl.DEPTH_COMPONENT24, whCube, whCube);
    gl.framebufferRenderbuffer(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.RENDERBUFFER, captureRBO);
    //----------------------------------------
    //createTexture bindTexture texImage2D
    envCubemap = gl.createTexture();
    gl.bindTexture(gl.TEXTURE_CUBE_MAP, envCubemap);
    for (let i = 0; i < 6; ++i) {
        gl.texImage2D(gl.TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, gl.RGBA16F, whCube, whCube, 0, gl.RGBA, gl.FLOAT, new Float32Array(whCube * whCube * 4));
    }
    gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
    gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
    gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_WRAP_R, gl.CLAMP_TO_EDGE);
    gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
    gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
    let captureProjection = mat4.create();
    mat4.perspective(captureProjection, (90.0) * Math.PI / 180.1.0.0.1.10.0);
    equirectangularToCubemapShader.use(gl);
    equirectangularToCubemapShader.setInt(gl, "equirectangularMap".0);
   gl.uniformMatrix4fv(gl.getUniformLocation(equirectangularToCubemapShader.programId, "projection"), false, captureProjection);
    //----------------------------------------
    // bindFramebuffer captureFBO framebufferTexture2D
    // framebufferTexture2D generates a map
    gl.activeTexture(gl.TEXTURE0);
    gl.bindTexture(gl.TEXTURE_2D, hdrTexture);
    gl.viewport(0.0, whCube, whCube);
    gl.bindFramebuffer(gl.FRAMEBUFFER, captureFBO);
    let captureViews = [
        mat4.lookAt(mat4.create(), vec3.fromValues(0.0.0.0.0.0), vec3.fromValues(1.0.0.0.0.0), vec3.fromValues(0.0, -1.0.0.0)),
        mat4.lookAt(mat4.create(), vec3.fromValues(0.0.0.0.0.0), vec3.fromValues(-1.0.0.0.0.0), vec3.fromValues(0.0, -1.0.0.0)),
        mat4.lookAt(mat4.create(), vec3.fromValues(0.0.0.0.0.0), vec3.fromValues(0.0.1.0.0.0), vec3.fromValues(0.0.0.0.1.0)),
        mat4.lookAt(mat4.create(), vec3.fromValues(0.0.0.0.0.0), vec3.fromValues(0.0, -1.0.0.0), vec3.fromValues(0.0.0.0, -1.0)),
        mat4.lookAt(mat4.create(), vec3.fromValues(0.0.0.0.0.0), vec3.fromValues(0.0.0.0.1.0), vec3.fromValues(0.0, -1.0.0.0)),
        mat4.lookAt(mat4.create(), vec3.fromValues(0.0.0.0.0.0), vec3.fromValues(0.0.0.0, -1.0), vec3.fromValues(0.0, -1.0.0.0))];for (let i = 0; i < 6; ++i) {
        gl.uniformMatrix4fv(gl.getUniformLocation(equirectangularToCubemapShader.programId, "view"), false, captureViews[i]);
        gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_CUBE_MAP_POSITIVE_X + i, envCubemap, 0);
        gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
        renderCube();
    }
    //----------------------------------------
    // bindFramebuffer null
    // createTexture bindTexture texImage2D texParameteri
    gl.bindFramebuffer(gl.FRAMEBUFFER, null);
    const whIrradiance = 32;
    irradianceMap = gl.createTexture();
    gl.bindTexture(gl.TEXTURE_CUBE_MAP, irradianceMap);
    for (let i = 0; i < 6; ++i) {
        gl.texImage2D(gl.TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, gl.RGBA16F, whIrradiance, whIrradiance, 0, gl.RGBA, gl.FLOAT, new Float32Array(whIrradiance * whIrradiance * 4));
    }
    gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
    gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
    gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_WRAP_R, gl.CLAMP_TO_EDGE);
    gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
    gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
    //----------------------------------------
    // bindFramebuffer bindRenderbuffer renderbufferStorage
    gl.bindFramebuffer(gl.FRAMEBUFFER, captureFBO);
    gl.bindRenderbuffer(gl.RENDERBUFFER, captureRBO);
    gl.renderbufferStorage(gl.RENDERBUFFER, gl.DEPTH_COMPONENT24, whIrradiance, whIrradiance);
    irradianceShader.use(gl);
    irradianceShader.setInt(gl, "environmentMap".0);
    gl.uniformMatrix4fv(gl.getUniformLocation(irradianceShader.programId, "projection"), false, captureProjection);
    gl.activeTexture(gl.TEXTURE0);
    gl.bindTexture(gl.TEXTURE_CUBE_MAP, envCubemap);
    gl.viewport(0.0, whIrradiance, whIrradiance);
    gl.bindFramebuffer(gl.FRAMEBUFFER, captureFBO);
    for (let i = 0; i < 6; ++i) {
        gl.uniformMatrix4fv(gl.getUniformLocation(irradianceShader.programId, "view"), false, captureViews[i]);
        gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_CUBE_MAP_POSITIVE_X + i, irradianceMap, 0);
        gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
        renderCube();
    }
    //----------------------------------------
    // bindFramebuffer
    gl.bindFramebuffer(gl.FRAMEBUFFER, null);
    mat4.perspective(projection, camera.Zoom, canvas.width / canvas.height, 0.1.100.0);
    pbrShader.use(gl);
    gl.uniformMatrix4fv(gl.getUniformLocation(pbrShader.programId, "projection"), false, projection);
    gl.uniform3fv(gl.getUniformLocation(pbrShader.programId, "lightPositions"), lightPositions);
    gl.uniform3fv(gl.getUniformLocation(pbrShader.programId, "lightColors"), lightColors);
    backgroundShader.use(gl);
    gl.uniformMatrix4fv(gl.getUniformLocation(backgroundShader.programId, "projection"), false, projection);
    gl.viewport(0.0, canvas.width, canvas.height);
    requestAnimationFrame(render);
}
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This is a drawcall to facilitate framebufferTexture2D mapping

function renderCube() {
    if(! cubeVAO) {let vertices = new Float32Array([-1.0, -1.0, -1.0.0.0.0.0, -1.0.0.0.0.0.1.0.1.0, -1.0.0.0.0.0, -1.0.1.0.1.0.1.0, -1.0, -1.0.0.0.0.0, -1.0.1.0.0.0.1.0.1.0, -1.0.0.0.0.0, -1.0.1.0.1.0,
            -1.0, -1.0, -1.0.0.0.0.0, -1.0.0.0.0.0,
            -1.0.1.0, -1.0.0.0.0.0, -1.0.0.0.1.0,
            -1.0, -1.0.1.0.0.0.0.0.1.0.0.0.0.0.1.0, -1.0.1.0.0.0.0.0.1.0.1.0.0.0.1.0.1.0.1.0.0.0.0.0.1.0.1.0.1.0.1.0.1.0.1.0.0.0.0.0.1.0.1.0.1.0,
            -1.0.1.0.1.0.0.0.0.0.1.0.0.0.1.0,
            -1.0, -1.0.1.0.0.0.0.0.1.0.0.0.0.0,
            -1.0.1.0.1.0, -1.0.0.0.0.0.1.0.0.0,
            -1.0.1.0, -1.0, -1.0.0.0.0.0.1.0.1.0,
            -1.0, -1.0, -1.0, -1.0.0.0.0.0.0.0.1.0,
            -1.0, -1.0, -1.0, -1.0.0.0.0.0.0.0.1.0,
            -1.0, -1.0.1.0, -1.0.0.0.0.0.0.0.0.0,
            -1.0.1.0.1.0, -1.0.0.0.0.0.1.0.0.0.1.0.1.0.1.0.1.0.0.0.0.0.1.0.0.0.1.0, -1.0, -1.0.1.0.0.0.0.0.0.0.1.0.1.0.1.0, -1.0.1.0.0.0.0.0.1.0.1.0.1.0, -1.0, -1.0.1.0.0.0.0.0.0.0.1.0.1.0.1.0.1.0.1.0.0.0.0.0.1.0.0.0.1.0, -1.0.1.0.1.0.0.0.0.0.0.0.0.0,
            -1.0, -1.0, -1.0.0.0, -1.0.0.0.0.0.1.0.1.0, -1.0, -1.0.0.0, -1.0.0.0.1.0.1.0.1.0, -1.0.1.0.0.0, -1.0.0.0.1.0.0.0.1.0, -1.0.1.0.0.0, -1.0.0.0.1.0.0.0,
            -1.0, -1.0.1.0.0.0, -1.0.0.0.0.0.0.0,
            -1.0, -1.0, -1.0.0.0, -1.0.0.0.0.0.1.0,
            -1.0.1.0, -1.0.0.0.1.0.0.0.0.0.1.0.1.0.1.0.1.0.0.0.1.0.0.0.1.0.0.0.1.0.1.0, -1.0.0.0.1.0.0.0.1.0.1.0.1.0.1.0.1.0.0.0.1.0.0.0.1.0.0.0,
            -1.0.1.0, -1.0.0.0.1.0.0.0.0.0.1.0,
            -1.0.1.0.1.0.0.0.1.0.0.0.0.0.0.0
        ]);
        cubeVAO = gl.createVertexArray();
        let cubeVBO = gl.createBuffer();
        gl.bindBuffer(gl.ARRAY_BUFFER, cubeVBO);
        gl.bufferData(gl.ARRAY_BUFFER, vertices, gl.STATIC_DRAW);
        gl.bindVertexArray(cubeVAO);
        gl.enableVertexAttribArray(0);
        gl.vertexAttribPointer(0.3, gl.FLOAT, false.8 * sizeFloat, 0);
        gl.enableVertexAttribArray(1);
        gl.vertexAttribPointer(1.3, gl.FLOAT, false.8 * sizeFloat, (3 * sizeFloat));
        gl.enableVertexAttribArray(2);
        gl.vertexAttribPointer(2.2, gl.FLOAT, false.8 * sizeFloat, (6 * sizeFloat));
        gl.bindBuffer(gl.ARRAY_BUFFER, null);
        gl.bindVertexArray(null);
    }
    gl.bindVertexArray(cubeVAO);
    gl.drawArrays(gl.TRIANGLES, 0.36);
    gl.bindVertexArray(null);
}
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Turn Hdr files into maps

let hdrTexture;
if (data) {
    let floats = rgbeToFloat(data); // Convert data to float data is the data in tocubeMap
    hdrTexture = gl.createTexture();
    gl.bindTexture(gl.TEXTURE_2D, hdrTexture);
    gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, true);
    gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGB16F, width, height, 0, gl.RGB, gl.FLOAT, floats);
    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
}
else {
    console.log("Failed to load HDR image.");
}
function rgbeToFloat(buffer) {
    var s, l = buffer.byteLength >> 2, res = res || new Float32Array(l * 3);
    for (var i = 0; i < l; i++) {
        s = Math.pow(2, buffer[i * 4 + 3] - (128 + 8));
        res[i * 3] = buffer[i * 4] * s;
        res[i * 3 + 1] = buffer[i * 4 + 1] * s;
        res[i * 3 + 2] = buffer[i * 4 + 2] * s;
    }
    return res;
}
function m(a, b) { for (var i in b)
    a[i] = b[i]; returna; };Copy the code

Reflection equation

The simplified equation

Diffuse reflection partial equation

HDR is converted to a floating point number group

Go through the cube and then get the six face map

Display the cube bounding box

The convolution of the cube map

PBR and indirect irradiance illumination

code

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