C++ OpenGL transformations

• Do multiple uniform assignments with a VAO and then drawCall

glBindVertexArray(VAO);
for (unsigned int i = 0; i < 10; i++)
{
    // calculate the model matrix for each object and pass it to shader before drawing
    glm::mat4 model = glm::mat4(1.0 f); // make sure to initialize matrix to identity matrix first
    model = glm::translate(model, cubePositions[i]);
    float angle = 20.0 f * i;
    model = glm::rotate(model, glm::radians(angle), glm::vec3(1.0 f.0.3 f.0.5 f));
    ourShader.setMat4("model", model);

    glDrawArrays(GL_TRIANGLES, 0.36);
}
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The original

#version 330 core
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec2 aTexCoord;

out vec2 TexCoord;

uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;

void main()
{
	gl_Position = projection * view * model * vec4(aPos, 1.0f);
	TexCoord = vec2(aTexCoord.x, aTexCoord.y);
}
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#version 330 core
out vec4 FragColor;

in vec2 TexCoord;

// texture samplers
uniform sampler2D texture1;
uniform sampler2D texture2;

void main()
{
	// linearly interpolate between both textures (80% container, 20% awesomeface)
	FragColor = mix(texture(texture1, TexCoord), texture(texture2, TexCoord), 0.2);
}
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#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <stb_image.h>

#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>

#include <learnopengl/shader_m.h>
#include <learnopengl/camera.h>

#include <iostream>

void framebuffer_size_callback(GLFWwindow* window, int width, int height);
void mouse_callback(GLFWwindow* window, double xpos, double ypos);
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset);
void processInput(GLFWwindow *window);

// settings
const unsigned int SCR_WIDTH = 800;
const unsigned int SCR_HEIGHT = 600;

// camera
Camera camera(glm::vec3(0.0 f.0.0 f.3.0 f));
float lastX = SCR_WIDTH / 2.0 f;
float lastY = SCR_HEIGHT / 2.0 f;
bool firstMouse = true;

// timing
float deltaTime = 0.0 f;	// time between current frame and last frame
float lastFrame = 0.0 f;

int main(a)
{
    // glfw: initialize and configure
    // ------------------------------
    glfwInit(a);glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

#ifdef __APPLE__
    glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
#endif

    // glfw window creation
    // --------------------
    GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL".NULL.NULL);
    if (window == NULL)
    {
        std::cout << "Failed to create GLFW window" << std::endl;
        glfwTerminate(a);return - 1;
    }
    glfwMakeContextCurrent(window);
    glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
    glfwSetCursorPosCallback(window, mouse_callback);
    glfwSetScrollCallback(window, scroll_callback);

    // tell GLFW to capture our mouse
    glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);

    // glad: load all OpenGL function pointers
    // ---------------------------------------
    if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
    {
        std::cout << "Failed to initialize GLAD" << std::endl;
        return - 1;
    }

    // configure global opengl state
    // -----------------------------
    glEnable(GL_DEPTH_TEST);

    // build and compile our shader zprogram
    // ------------------------------------
    Shader ourShader("7.4. Camera. Vs."."7.4. Camera. The fs");

    // set up vertex data (and buffer(s)) and configure vertex attributes
    // ------------------------------------------------------------------
    float vertices[] = {
        0.5 f.0.5 f.0.5 f.0.0 f.0.0 f.0.5 f.0.5 f.0.5 f.1.0 f.0.0 f.0.5 f.0.5 f.0.5 f.1.0 f.1.0 f.0.5 f.0.5 f.0.5 f.1.0 f.1.0 f.0.5 f.0.5 f.0.5 f.0.0 f.1.0 f.0.5 f.0.5 f.0.5 f.0.0 f.0.0 f.0.5 f.0.5 f.0.5 f.0.0 f.0.0 f.0.5 f.0.5 f.0.5 f.1.0 f.0.0 f.0.5 f.0.5 f.0.5 f.1.0 f.1.0 f.0.5 f.0.5 f.0.5 f.1.0 f.1.0 f.0.5 f.0.5 f.0.5 f.0.0 f.1.0 f.0.5 f.0.5 f.0.5 f.0.0 f.0.0 f.0.5 f.0.5 f.0.5 f.1.0 f.0.0 f.0.5 f.0.5 f.0.5 f.1.0 f.1.0 f.0.5 f.0.5 f.0.5 f.0.0 f.1.0 f.0.5 f.0.5 f.0.5 f.0.0 f.1.0 f.0.5 f.0.5 f.0.5 f.0.0 f.0.0 f.0.5 f.0.5 f.0.5 f.1.0 f.0.0 f.0.5 f.0.5 f.0.5 f.1.0 f.0.0 f.0.5 f.0.5 f.0.5 f.1.0 f.1.0 f.0.5 f.0.5 f.0.5 f.0.0 f.1.0 f.0.5 f.0.5 f.0.5 f.0.0 f.1.0 f.0.5 f.0.5 f.0.5 f.0.0 f.0.0 f.0.5 f.0.5 f.0.5 f.1.0 f.0.0 f.0.5 f.0.5 f.0.5 f.0.0 f.1.0 f.0.5 f.0.5 f.0.5 f.1.0 f.1.0 f.0.5 f.0.5 f.0.5 f.1.0 f.0.0 f.0.5 f.0.5 f.0.5 f.1.0 f.0.0 f.0.5 f.0.5 f.0.5 f.0.0 f.0.0 f.0.5 f.0.5 f.0.5 f.0.0 f.1.0 f.0.5 f.0.5 f.0.5 f.0.0 f.1.0 f.0.5 f.0.5 f.0.5 f.1.0 f.1.0 f.0.5 f.0.5 f.0.5 f.1.0 f.0.0 f.0.5 f.0.5 f.0.5 f.1.0 f.0.0 f.0.5 f.0.5 f.0.5 f.0.0 f.0.0 f.0.5 f.0.5 f.0.5 f.0.0 f.1.0 f
    };
    // world space positions of our cubes
    glm::vec3 cubePositions[] = {
        glm::vec3( 0.0 f.0.0 f.0.0 f),
        glm::vec3( 2.0 f.5.0 f.15.0 f),
        glm::vec3(1.5 f.2.2 f.2.5 f),
        glm::vec3(3.8 f.2.0 f.12.3 f),
        glm::vec3( 2.4 f.0.4 f.3.5 f),
        glm::vec3(1.7 f.3.0 f.7.5 f),
        glm::vec3( 1.3 f.2.0 f.2.5 f),
        glm::vec3( 1.5 f.2.0 f.2.5 f),
        glm::vec3( 1.5 f.0.2 f.1.5 f),
        glm::vec3(1.3 f.1.0 f.1.5 f)};unsigned int VBO, VAO;
    glGenVertexArrays(1, &VAO);
    glGenBuffers(1, &VBO);

    glBindVertexArray(VAO);

    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

    // position attribute
    glVertexAttribPointer(0.3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(0);
    // texture coord attribute
    glVertexAttribPointer(1.2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void(*)3 * sizeof(float)));
    glEnableVertexAttribArray(1);


    // load and create a texture 
    // -------------------------
    unsigned int texture1, texture2;
    // texture 1
    // ---------
    glGenTextures(1, &texture1);
    glBindTexture(GL_TEXTURE_2D, texture1);
    // set the texture wrapping parameters
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
    // set texture filtering parameters
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    // load image, create texture and generate mipmaps
    int width, height, nrChannels;
    stbi_set_flip_vertically_on_load(true); // tell stb_image.h to flip loaded texture's on the y-axis.
    unsigned char *data = stbi_load(FileSystem::getPath("resources/textures/container.jpg").c_str(), &width, &height, &nrChannels, 0);
    if (data)
    {
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data);
        glGenerateMipmap(GL_TEXTURE_2D);
    }
    else
    {
        std::cout << "Failed to load texture" << std::endl;
    }
    stbi_image_free(data);
    // texture 2
    // ---------
    glGenTextures(1, &texture2);
    glBindTexture(GL_TEXTURE_2D, texture2);
    // set the texture wrapping parameters
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
    // set texture filtering parameters
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    // load image, create texture and generate mipmaps
    data = stbi_load(FileSystem::getPath("resources/textures/awesomeface.png").c_str(), &width, &height, &nrChannels, 0);
    if (data)
    {
        // note that the awesomeface.png has transparency and thus an alpha channel, so make sure to tell OpenGL the data type is of GL_RGBA
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);
        glGenerateMipmap(GL_TEXTURE_2D);
    }
    else
    {
        std::cout << "Failed to load texture" << std::endl;
    }
    stbi_image_free(data);

    // tell opengl for each sampler to which texture unit it belongs to (only has to be done once)
    // -------------------------------------------------------------------------------------------
    ourShader.use(a); ourShader.setInt("texture1".0);
    ourShader.setInt("texture2".1);


    // render loop
    // -----------
    while (!glfwWindowShouldClose(window))
    {
        // per-frame time logic
        // --------------------
        float currentFrame = glfwGetTime(a); deltaTime = currentFrame - lastFrame; lastFrame = currentFrame;// input
        // -----
        processInput(window);

        // render
        // ------
        glClearColor(0.2 f.0.3 f.0.3 f.1.0 f);
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); 

        // bind textures on corresponding texture units
        glActiveTexture(GL_TEXTURE0);
        glBindTexture(GL_TEXTURE_2D, texture1);
        glActiveTexture(GL_TEXTURE1);
        glBindTexture(GL_TEXTURE_2D, texture2);

        // activate shader
        ourShader.use(a);// pass projection matrix to shader (note that in this case it could change every frame)
        glm::mat4 projection = glm::perspective(glm::radians(camera.Zoom), (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1 f.100.0 f);
        ourShader.setMat4("projection", projection);

        // camera/view transformation
        glm::mat4 view = camera.GetViewMatrix(a); ourShader.setMat4("view", view);

        // render boxes
        glBindVertexArray(VAO);
        for (unsigned int i = 0; i < 10; i++)
        {
            // calculate the model matrix for each object and pass it to shader before drawing
            glm::mat4 model = glm::mat4(1.0 f); // make sure to initialize matrix to identity matrix first
            model = glm::translate(model, cubePositions[i]);
            float angle = 20.0 f * i;
            model = glm::rotate(model, glm::radians(angle), glm::vec3(1.0 f.0.3 f.0.5 f));
            ourShader.setMat4("model", model);

            glDrawArrays(GL_TRIANGLES, 0.36);
        }

        // glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.)
        // -------------------------------------------------------------------------------
        glfwSwapBuffers(window);
        glfwPollEvents(a); }// optional: de-allocate all resources once they've outlived their purpose:
    // ------------------------------------------------------------------------
    glDeleteVertexArrays(1, &VAO);
    glDeleteBuffers(1, &VBO);

    // glfw: terminate, clearing all previously allocated GLFW resources.
    // ------------------------------------------------------------------
    glfwTerminate(a);return 0;
}

// process all input: query GLFW whether relevant keys are pressed/released this frame and react accordingly
// ---------------------------------------------------------------------------------------------------------
void processInput(GLFWwindow *window)
{
    if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
        glfwSetWindowShouldClose(window, true);

    if (glfwGetKey(window, GLFW_KEY_W) == GLFW_PRESS)
        camera.ProcessKeyboard(FORWARD, deltaTime);
    if (glfwGetKey(window, GLFW_KEY_S) == GLFW_PRESS)
        camera.ProcessKeyboard(BACKWARD, deltaTime);
    if (glfwGetKey(window, GLFW_KEY_A) == GLFW_PRESS)
        camera.ProcessKeyboard(LEFT, deltaTime);
    if (glfwGetKey(window, GLFW_KEY_D) == GLFW_PRESS)
        camera.ProcessKeyboard(RIGHT, deltaTime);
}

// glfw: whenever the window size changed (by OS or user resize) this callback function executes
// ---------------------------------------------------------------------------------------------
void framebuffer_size_callback(GLFWwindow* window, int width, int height)
{
    // make sure the viewport matches the new window dimensions; note that width and 
    // height will be significantly larger than specified on retina displays.
    glViewport(0.0, width, height);
}


// glfw: whenever the mouse moves, this callback is called
// -------------------------------------------------------
void mouse_callback(GLFWwindow* window, double xpos, double ypos)
{
    if (firstMouse)
    {
        lastX = xpos;
        lastY = ypos;
        firstMouse = false;
    }

    float xoffset = xpos - lastX;
    float yoffset = lastY - ypos; // reversed since y-coordinates go from bottom to top

    lastX = xpos;
    lastY = ypos;

    camera.ProcessMouseMovement(xoffset, yoffset);
}

// glfw: whenever the mouse scroll wheel scrolls, this callback is called
// ----------------------------------------------------------------------
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset)
{
    camera.ProcessMouseScroll(yoffset);
}
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