Let’s write a comprehensive case using what we learned about OpenGL at the front door
First, the effect drawing
Ii. Flow chart
Three, the source code
#include "GLTools.h"
#include "GLShaderManager.h"
#include "GLFrustum.h"
#include "GLBatch.h"
#include "GLMatrixStack.h"
#include "GLGeometryTransform.h"
#include "StopWatch.h"//定时
#include <math.h>
#include <stdio.h>
#ifdef __APPLE__
#include <glut/glut.h>
#else
#define FREEGLUT_STATIC
#include <GL/glut.h>
#endif
GLShaderManager shaderManager; // 着色器管理器
GLMatrixStack modelViewMatrix; // 模型视图矩阵
GLMatrixStack projectionMatrix; // 投影矩阵
GLFrustum viewFrustum; // 视景体
GLGeometryTransform transformPipeline; // 几何图形变换管道
GLTriangleBatch torusBatch; //大球
GLTriangleBatch sphereBatch; //小球
GLBatch floorBatch; //地板
GLFrame cameraFrame;
//添加50个随机小球
#define NUM_SPHERES 50
GLFrame spheres[NUM_SPHERES];
//纹理标记数组
GLuint uiTextures[3];
bool LoadTGATexture(const char *szFileName, GLenum minFilter, GLenum magFilter, GLenum wrapMode)
{
//初始化需要用到的参数
GLbyte *pBits;
int nWidth,nHeight,nComponents;
GLenum eFormat;
//读取到上面的数据
pBits = gltReadTGABits(szFileName, &nWidth, &nHeight, &nComponents, &eFormat);
if (pBits == NULL) {
return false;
}
//设置纹理
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, wrapMode);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, wrapMode);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, minFilter);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, magFilter);
//载入纹理
/*
参数1：纹理维度
参数2：mip贴图层次
参数3：纹理单元存储的颜色成分（从读取像素图是获得）-将内部参数nComponents改为了通用压缩纹理格式GL_COMPRESSED_RGB
参数4：加载纹理宽
参数5：加载纹理高
参数6：加载纹理的深度
参数7：像素数据的数据类型（GL_UNSIGNED_BYTE，每个颜色分量都是一个8位无符号整数）
参数8：指向纹理图像数据的指针
*/
glTexImage2D(GL_TEXTURE_2D, 0, GL_COMPRESSED_RGB, nWidth, nHeight, 0,eFormat, GL_UNSIGNED_BYTE, pBits);
//释放pBits
free(pBits);
//如果是以下4种过滤方式，才生产MIP贴图
if(
minFilter == GL_LINEAR_MIPMAP_LINEAR ||
minFilter == GL_LINEAR_MIPMAP_NEAREST ||
minFilter == GL_NEAREST_MIPMAP_LINEAR ||
minFilter == GL_NEAREST_MIPMAP_NEAREST
){
//加载Mip,纹理生成所有的Mip层
glGenerateMipmap(GL_TEXTURE_2D);
}
return true;
}
void SetupRC()
{
//1、设置背景色
glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
//2、初始化着色器
shaderManager.InitializeStockShaders();
//3、开始深度测试、正背面剔除
glEnable(GL_DEPTH_TEST);
glEnable(GL_CULL_FACE);
//4、初始化地板（添加顶点数据和纹理坐标）
GLfloat texSize = 10.0f;
floorBatch.Begin(GL_TRIANGLE_FAN, 4,1);
floorBatch.MultiTexCoord2f(0, 0.0f, 0.0f);
floorBatch.Vertex3f(-20.f, -0.41f, 20.0f);
floorBatch.MultiTexCoord2f(0, texSize, 0.0f);
floorBatch.Vertex3f(20.0f, -0.41f, 20.f);
floorBatch.MultiTexCoord2f(0, texSize, texSize);
floorBatch.Vertex3f(20.0f, -0.41f, -20.0f);
floorBatch.MultiTexCoord2f(0, 0.0f, texSize);
floorBatch.Vertex3f(-20.0f, -0.41f, -20.0f);
floorBatch.End();
//5、初始化自转大球
gltMakeSphere(torusBatch, 0.4f, 40, 80);
//6、初始化自转+公转的小球
gltMakeSphere(sphereBatch, 0.1f, 12, 24);
//7、设置50个随机位置的小球
for (int i=0; i<NUM_SPHERES; i++) {
//因为都在一个平面，Y值是不变的。X和Z是随机的
GLfloat x = ((GLfloat)((rand() % 400) - 200 ) * 0.1f);
GLfloat z = ((GLfloat)((rand() % 400) - 200 ) * 0.1f);
//对spheres数组中的每一个顶点，设置顶点数据(SetOrigin设置位置)
spheres[i].SetOrigin(x, 0.0f, z);
}
//8、初始化纹理-申请3个纹理
glGenTextures(3, uiTextures);
//9、绑定各个纹理，并且读取TGA文件参数并进行设置
glBindTexture(GL_TEXTURE_2D, uiTextures[0]);
LoadTGATexture("marble.tga",
GL_LINEAR_MIPMAP_LINEAR,
GL_LINEAR,
GL_REPEAT);
glBindTexture(GL_TEXTURE_2D, uiTextures[1]);
LoadTGATexture("marslike.tga",
GL_LINEAR_MIPMAP_LINEAR,
GL_LINEAR,
GL_CLAMP_TO_EDGE);
glBindTexture(GL_TEXTURE_2D, uiTextures[2]);
LoadTGATexture("moonlike.tga",
GL_LINEAR_MIPMAP_LINEAR,
GL_LINEAR,
GL_CLAMP_TO_EDGE);
}
//删除纹理
void ShutdownRC(void)
{
glDeleteTextures(3, uiTextures);
}
void drawSomething(GLfloat yRot)
{
//1、定义光源位置和漫反射颜色
static GLfloat vWhite[] = { 1.0f, 1.0f, 1.0f, 1.0f };
static GLfloat vLightPos[] = { 0.0f, 3.0f, 0.0f, 1.0f };
//2、绘制50个随机小球
//先设置纹理-2号纹理
glBindTexture(GL_TEXTURE_2D, uiTextures[2]);
//循环把每个小球位置放进栈中,并绘制出来
//因为小球是几何模型，所以不需要绑定纹理坐标
for(int i = 0; i < NUM_SPHERES; i++) {
modelViewMatrix.PushMatrix();
modelViewMatrix.MultMatrix(spheres[i]);
/*
参数1: 存储着⾊器种类-纹理光源着⾊器 GLT_SHADER_TEXTURE_POINT_LIGHT_DIEF
参数2: 模型4*4矩阵
参数3: 投影4*4矩阵
参数4: 点光源位置
参数5: 颜⾊值(⼏何图形的基本⾊)
参数6: 纹理单元
*/
shaderManager.UseStockShader(GLT_SHADER_TEXTURE_POINT_LIGHT_DIFF,
modelViewMatrix.GetMatrix(),
transformPipeline.GetProjectionMatrix(),
vLightPos,
vWhite,
0);
sphereBatch.Draw();
modelViewMatrix.PopMatrix();
}
//把所有图案都平移一下。先Y轴平移一点点，再Z轴平移一点点
modelViewMatrix.Translate(0.0f, 0.2f, -2.5f);
//3、绘制大球
modelViewMatrix.PushMatrix();
modelViewMatrix.Rotate(yRot, 0.0f, 1.0f, 0.0f);
glBindTexture(GL_TEXTURE_2D, uiTextures[1]);
shaderManager.UseStockShader(GLT_SHADER_TEXTURE_POINT_LIGHT_DIFF,
modelViewMatrix.GetMatrix(),
transformPipeline.GetProjectionMatrix(),
vLightPos,
vWhite,
0);
torusBatch.Draw();
modelViewMatrix.PopMatrix();
//4、绘制公转自转小球
modelViewMatrix.PushMatrix();
modelViewMatrix.Rotate(yRot * -2.0f, 0.0f, 1.0f, 0.0f);
modelViewMatrix.Translate(0.8f, 0.0f, 0.0f);
glBindTexture(GL_TEXTURE_2D, uiTextures[2]);
shaderManager.UseStockShader(GLT_SHADER_TEXTURE_POINT_LIGHT_DIFF,
modelViewMatrix.GetMatrix(),
transformPipeline.GetProjectionMatrix(),
vLightPos,
vWhite,
0);
sphereBatch.Draw();
modelViewMatrix.PopMatrix();
}
void RenderScene(void)
{
//1、设置必要的参数
//地板颜色
static GLfloat vFloorColor[] = {1.0f,1.0f,0.0f,0.75f};
//基于时间的旋转角度
static CStopWatch rotTimer;
float yRot = rotTimer.GetElapsedSeconds() * 60.f;
//清空颜色缓冲区和深度缓冲区
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
//2、压栈，是为了保证整个画面绘制完之后，清空，不影响下一次绘制
modelViewMatrix.PushMatrix();
//3、压入观察者，因为观察者一旦变化，所有东西都会变化。其他的变化其实是基于观察者变化之上的。
M3DMatrix44f mCamera;
cameraFrame.GetCameraMatrix(mCamera);
modelViewMatrix.MultMatrix(mCamera);
//4、画镜面部分。这里也要加一次push、pop。因为镜面部分和镜面之上是分开的，没有联动，不能让镜面对其他地方造成影响
//镜面push （这里push的是观察者矩阵）
modelViewMatrix.PushMatrix();
//围绕Y轴翻转，所以顶点都发生了改变
modelViewMatrix.Scale(1.0f, -1.0f, 1.0f);
//为了效果逼真，把镜面与镜面之上隔开距离，沿着Y轴偏移一下
modelViewMatrix.Translate(0.0f, 0.8f, 0.0f);
//因为镜面和正常是反的，所以要声明一下，让顺时针成为正面
glFrontFace(GL_CW);
//开始绘制镜面所显示的东西
drawSomething(yRot);
//镜面画完之后要把正面恢复成逆时针
glFrontFace(GL_CCW);
//镜面pop
modelViewMatrix.PopMatrix();
//5、画地板部分，然后和镜面部分混合一下（是为了能够看到地板以下的镜面部分）。 因为地板从始至终没有发生变化，所以不需要压栈出栈
//开启混合
glEnable(GL_BLEND);
//指定颜色混合方程式
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
//绑定地板纹理
glBindTexture(GL_TEXTURE_2D, uiTextures[0]);
//使用着色器
/*
参数1: 存储着⾊器种类-纹理调整着⾊器 GLT_SHADER_TEXTURE_MODULATE
参数2: 模型4*4矩阵
参数3: 颜⾊值
参数4: 纹理单元
*/
shaderManager.UseStockShader(GLT_SHADER_TEXTURE_MODULATE,transformPipeline.GetModelViewProjectionMatrix(),vFloorColor,0);
//绘制
floorBatch.Draw();
//关闭混合
glDisable(GL_BLEND);
//6、画地板之上的正常区域
//其实这个地方是要加push、pop的，但是因为，这一块是最后绘制的，它对其他地方没有影响，就可以省略了
drawSomething(yRot);
//7、出栈
modelViewMatrix.PopMatrix();
//8、交换缓冲区
glutSwapBuffers();
//9、因为开启了定时器，我们要不断刷新渲染
glutPostRedisplay();
}
void ChangeSize(int w, int h)
{
if (h == 0) {
h = 1;
}
glViewport(0, 0, w, h);
viewFrustum.SetPerspective(35.0f, float(w)/float(h), 1.0f, 150.0f);
projectionMatrix.LoadMatrix(viewFrustum.GetProjectionMatrix());
transformPipeline.SetMatrixStacks(modelViewMatrix, projectionMatrix);
}
void SpeacialKeys(int key,int x,int y)
{
if (key == GLUT_KEY_UP) {
//MoveForward 平移
cameraFrame.MoveForward(0.1f);
}
if (key == GLUT_KEY_DOWN) {
cameraFrame.MoveForward(-0.1f);
}
if (key == GLUT_KEY_LEFT) {
//RotateWorld 旋转
cameraFrame.RotateWorld(m3dDegToRad(5.0f), 0.0f, 1.0f, 0.0f);
}
if (key == GLUT_KEY_RIGHT) {
cameraFrame.RotateWorld(m3dDegToRad(-5.0f), 0.0f, 1.0f, 0.0f);
}
//本里这里需要移动后重新渲染的，但是因为渲染方法中，因为定时器问题本身就一直再重新渲染，这里就不用再写一遍了，啰嗦
// glutPostRedisplay();
}
int main(int argc, char* argv[])
{
gltSetWorkingDirectory(argv[0]);
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
glutInitWindowSize(800,600);
glutCreateWindow("球体世界");
GLenum err = glewInit();
if (GLEW_OK != err) {
fprintf(stderr, "GLEW Error: %s\n", glewGetErrorString(err));
return 1;
}
glutReshapeFunc(ChangeSize);
glutDisplayFunc(RenderScene);
glutSpecialFunc(SpeacialKeys);
SetupRC();
glutMainLoop();
ShutdownRC();
return 0;
}
Copy the codeFour, notes
- Shader use: large ball ball – texture point light shader; Floor – Texture adjustment shader.
- Big ball rotation: To visualize the big ball, we need to translate it. Then push the stack and rotate (if you put a translation in the stack, it will be shifted with each turn).
- Ball rotation + revolution: pressing, must pay attention to the rotationTranslation. Because pushing doesn’t satisfy the commutative law. If it’s a translationRotation is another effect.
- Mirror floor: in fact, the bottom of the thing is written again, and then mixed with the floor texture formed.
- Since there are two draws and renderings for all balls, we encapsulate a drawSomething method and call it directly twice to save code
- The position of the graphics changes with each move, so the first thing to do in RenderSence after pushing is to put the Camera name in.
- Remember to pop every push.
- In fact, we can see the full picture of the case if we zoom out:
