OpenGL代码学习（15）--理解透视投影矩阵
作者：互联网
注意：需要在配置好OpenGL的编程环境中运行下列代码，环境配置文章可参考：
OpenGL在Mac项目上的配置
下面的代码，直接放置在main.cpp文件中即可：
#include "GLTools.h"
#include "GLMatrixStack.h"
#include "GLFrame.h"
#include "GLFrustum.h"
#include "GLGeometryTransform.h"
#include "GLBatch.h"
#include "math.h"
#include <GLUT/GLUT.h>
GLFrame viewFrame;
GLFrustum viewFrustum;
GLBatch tubeBatch;
GLBatch innerBatch;
GLMatrixStack modelViewMatix;
GLMatrixStack projectionMatrix;
GLGeometryTransform transformPipeline;
GLShaderManager shaderManager;
float fZ = 100.0f;
float bZ = -100.0f;
// 窗口渲染调用
void RenderScene(void) {
// 清除缓存区
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
// 压栈，物体矩阵
modelViewMatix.PushMatrix(viewFrame);
// 默认红色光源着色
GLfloat vRed[] = { 1.0f, 0.0f, 0.0f, 1.0f };
shaderManager.UseStockShader(GLT_SHADER_DEFAULT_LIGHT, transformPipeline.GetModelViewMatrix(), transformPipeline.GetProjectionMatrix(), vRed);
tubeBatch.Draw();
// 默认灰色光源着色
GLfloat vGray[] = { 0.75f, 0.75f, 0.75f, 1.0f };
shaderManager.UseStockShader(GLT_SHADER_DEFAULT_LIGHT, transformPipeline.GetModelViewMatrix(), transformPipeline.GetProjectionMatrix(), vGray);
innerBatch.Draw();
// 出栈，还原为单位矩阵
modelViewMatix.PopMatrix();
// 双缓存模式，后台缓存切换到前台进行显示
glutSwapBuffers();
}
void SetupTubeBatch() {
tubeBatch.Begin(GL_QUADS, 200);
tubeBatch.Color4f(1.0f, 0.0f, 0.0f, 1.0f);
// 后面
GLfloat vBack[] = {
// Left Pannel
-50.0f, 50.0f, fZ,
-50.0f, -50.0f, fZ,
-35.0f, -50.0f, fZ,
-35.0f, 50.0f, fZ,
// Right Panel
50.0f, 50.0f, fZ,
35.0f, 50.0f, fZ,
35.0f, -50.0f, fZ,
50.0f,-50.0f, fZ,
// Top Panel
-35.0f, 50.0f, fZ,
-35.0f, 35.0f, fZ,
35.0f, 35.0f, fZ,
35.0f, 50.0f, fZ,
// Bottom Panel
-35.0f, -35.0f, fZ,
-35.0f, -50.0f, fZ,
35.0f, -50.0f, fZ,
35.0f, -35.0f, fZ
};
for(int i = 0; i < 16; i++) {
int index = i * 3;
tubeBatch.Normal3f(0.0f, 0.0f, 1.0f);
tubeBatch.Vertex3f(vBack[index], vBack[index+1], vBack[index+2]);
}
// 前面
GLfloat vFront[] = {
// Left Pannel
-35.0f, 50.0f, bZ,
-35.0f, -50.0f, bZ,
-50.0f, -50.0f, bZ,
-50.0f, 50.0f, bZ,
// Right Panel
50.0f, -50.0f, bZ,
35.0f, -50.0f, bZ,
35.0f, 50.0f, bZ,
50.0f, 50.0f, bZ,
// Top Panel
35.0f, 50.0f, bZ,
35.0f, 35.0f, bZ,
-35.0f, 35.0f, bZ,
-35.0f, 50.0f, bZ,
// Bottom Panel
35.0f, -35.0f, bZ,
35.0f, -50.0f, bZ,
-35.0f, -50.0f, bZ,
-35.0f, -35.0f, bZ
};
for(int i = 0; i < 16; i++) {
int index = i * 3;
tubeBatch.Normal3f(0.0f, 0.0f, -1.0f);
tubeBatch.Vertex3f(vFront[index], vFront[index+1], vFront[index+2]);
}
// 上面
GLfloat vTop[] = {
-50.0f, 50.0f, fZ,
50.0f, 50.0f, fZ,
50.0f, 50.0f, bZ,
-50.0f, 50.0f, bZ
};
for(int i = 0; i < 4; i++) {
int index = i * 3;
tubeBatch.Normal3f(0.0f, 1.0f, 0.0f);
tubeBatch.Vertex3f(vTop[index], vTop[index+1], vTop[index+2]);
}
// 下面
GLfloat vBottom[] = {
-50.0f, -50.0f, fZ,
-50.0f, -50.0f, bZ,
50.0f, -50.0f, bZ,
50.0f, -50.0f, fZ
};
for(int i = 0; i < 4; i++) {
int index = i * 3;
tubeBatch.Normal3f(0.0f, -1.0f, 0.0f);
tubeBatch.Vertex3f(vBottom[index], vBottom[index+1], vBottom[index+2]);
}
// 左面
GLfloat vLeft[] = {
50.0f, 50.0f, fZ,
50.0f, -50.0f, fZ,
50.0f, -50.0f, bZ,
50.0f, 50.0f, bZ
};
for(int i = 0; i < 4; i++) {
int index = i * 3;
tubeBatch.Normal3f(1.0f, 0.0f, 0.0f);
tubeBatch.Vertex3f(vLeft[index], vLeft[index+1], vLeft[index+2]);
}
// 右面
GLfloat vRight[] = {
-50.0f, 50.0f, fZ,
-50.0f, 50.0f, bZ,
-50.0f, -50.0f, bZ,
-50.0f, -50.0f, fZ
};
for(int i = 0; i < 4; i++) {
int index = i * 3;
tubeBatch.Normal3f(-1.0f, 0.0f, 0.0f);
tubeBatch.Vertex3f(vRight[index], vRight[index+1], vRight[index+2]);
}
tubeBatch.End();
}
void SetupInnerBatch() {
innerBatch.Begin(GL_QUADS, 40);
innerBatch.Color4f(0.75f, 0.75f, 0.75f, 1.0f);
// 上面
GLfloat innerTop[] = {
-35.0f, 35.0f, fZ,
35.0f, 35.0f, fZ,
35.0f, 35.0f, bZ,
-35.0f, 35.0f, bZ
};
for(int i = 0; i < 4; i++) {
int index = i * 3;
innerBatch.Normal3f(0.0f, -1.0f, 0.0f);
innerBatch.Vertex3f(innerTop[index], innerTop[index+1], innerTop[index+2]);
}
// 下面
GLfloat innerBottom[] = {
-35.0f, -35.0f, fZ,
-35.0f, -35.0f, bZ,
35.0f, -35.0f, bZ,
35.0f, -35.0f, fZ
};
for(int i = 0; i < 4; i++) {
int index = i * 3;
innerBatch.Normal3f(0.0f, 1.0f, 0.0f);
innerBatch.Vertex3f(innerBottom[index], innerBottom[index+1], innerBottom[index+2]);
}
// 左面
GLfloat innerLeft[] = {
35.0f, 35.0f, fZ,
35.0f, -35.0f, fZ,
35.0f, -35.0f, bZ,
35.0f, 35.0f, bZ
};
for(int i = 0; i < 4; i++) {
int index = i * 3;
innerBatch.Normal3f(-1.0f, 0.0f, 0.0f);
innerBatch.Vertex3f(innerLeft[index], innerLeft[index+1], innerLeft[index+2]);
}
// 右面
GLfloat innerRight[] = {
-35.0f, 35.0f, fZ,
-35.0f, 35.0f, bZ,
-35.0f, -35.0f, bZ,
-35.0f, -35.0f, fZ
};
for(int i = 0; i < 4; i++) {
int index = i * 3;
innerBatch.Normal3f(1.0f, 0.0f, 0.0f);
innerBatch.Vertex3f(innerRight[index], innerRight[index+1], innerRight[index+2]);
}
innerBatch.End();
}
// 程序初始化环境
void SetupRC() {
// 设置背景颜色为淡蓝色
glClearColor(0.0f, 0.0f, 0.75f, 1.0f);
// 开启深度测试
glEnable(GL_DEPTH_TEST);
// 着色器初始化
shaderManager.InitializeStockShaders();
// 物体向里面移动 450 距离
viewFrame.MoveForward(450.0f);
// 创建长方体暴露在外面的红色面
SetupTubeBatch();
// 创建长方体里面的灰色面
SetupInnerBatch();
}
void SpecialKeys(int key, int x, int y) {
// 按下上、下、左、右方向键，对物体进行旋转，m3dDegToRad = 角度 -> 弧度
switch(key) {
case GLUT_KEY_UP:
// angle=-5, x=1, y=0, z=0 表示绕x轴正方向顺时针旋转(从x轴正方向看去)
viewFrame.RotateWorld(m3dDegToRad(-5.0f), 1.0f, 0.0f, 0.0f);
break;
case GLUT_KEY_DOWN:
// angle=5, x=1, y=0, z=0 表示绕x轴正方向逆时针旋转(从x轴正方向看去)
viewFrame.RotateWorld(m3dDegToRad(5.0f), 1.0f, 0.0f, 0.0f);
break;
case GLUT_KEY_LEFT:
// angle=-5, x=0, y=1, z=0 表示绕y轴正方向顺时针旋转(从y轴正方向看去)
viewFrame.RotateWorld(m3dDegToRad(-5.0f), 0.0f, 1.0f, 0.0f);
break;
case GLUT_KEY_RIGHT:
// angle=5, x=0, y=1, z=0 表示绕y轴正方向逆时针旋转(从y轴正方向看去)
viewFrame.RotateWorld(m3dDegToRad(5.0f), 0.0f, 1.0f, 0.0f);
break;
}
// 重写渲染窗口
glutPostRedisplay();
}
// 窗口变换回调
void ChangeSize(int width, int height) {
// 防止除数为0
if(height == 0)
height = 1;
// 设置视口
glViewport(0, 0, width, height);
// 设置透视投影矩阵，参数分别为：透视角，宽高比，近距，远距
viewFrustum.SetPerspective(35.0f, float(width)/float(height), 1.0f, 1000.0f);
// 保持透视投影矩阵
projectionMatrix.LoadMatrix(viewFrustum.GetProjectionMatrix());
// 利用变换管线，管理2个堆栈
transformPipeline.SetMatrixStacks(modelViewMatix, projectionMatrix);
}
// 程序入口
int main(int argc, char* argv[]) {
// 针对 Mac OS 设置工作目录路径
gltSetWorkingDirectory(argv[0]);
// 初始化 GLUT
glutInit(&argc, argv);
// 初始化渲染模式
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA | GLUT_DEPTH | GLUT_STENCIL);
// 初始化窗口大小
glutInitWindowSize(800, 720);
// 创建窗口并命名
glutCreateWindow("Perspective Projection Example");
// 检测驱动程序是否初始化成功
GLenum err = glewInit();
if (GLEW_OK != err) {
fprintf(stderr, "GLEW Error: %s\n", glewGetErrorString(err));
return 1;
}
// 窗口大小改变回调函数设置
glutReshapeFunc(ChangeSize);
// 特殊按键点击回调函数设置
glutSpecialFunc(SpecialKeys);
// 窗口渲染回调函数设置
glutDisplayFunc(RenderScene);
// 程序初始化环境
SetupRC();
// 主消息循环
glutMainLoop();
return 0;
}
效果图如下所示：
标签：index,15,OpenGL,--,0.0,35.0,fZ,50.0,bZ 来源： https://www.cnblogs.com/cchHers/p/14726477.html