一、Mac 配置OpenGL环境
可参考 OpenGL Mac环境配置
二、绘制三角形
三角形绘制流程.jpeg
代码如下：
(1) 引入头文件
#include "GLShaderManager.h"
#include "GLTools.h"
#include <GLUT/GLUT.h>
(2)定义工具类对象（着色器管理类、三角形批次类）
GLShaderManager shaderManager;
GLBatch triangleBatch;
(3)入口函数Main（初始化）
int main(int argc,char *argv[])
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGBA|GLUT_DEPTH|GLUT_STENCIL);
glutInitWindowSize(800, 600);
glutCreateWindow("Triangle");
glutReshapeFunc(changeSize);
glutDisplayFunc(RenderScene);
GLenum status = glewInit();
if (GLEW_OK != status) {
printf("GLEW Error:%s\n",glewGetErrorString(status));
return 1;
}
setupRC();
glutMainLoop();
return 0;
}
(4)初始化setupRC
void setupRC()
{
glClearColor(0.98f, 0.40f, 0.7f, 1);
shaderManager.InitializeStockShaders();
GLfloat vVerts[] = {
-0.5f,0.0f,0.0f,
0.5f,0.0f,0.0f,
0.0f,0.5f,0.0f
};
triangleBatch.Begin(GL_TRIANGLES, 3);
triangleBatch.CopyVertexData3f(vVerts);
triangleBatch.End();
}
(5)消息循环--渲染回调
void RenderScene(void)
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT|GL_STENCIL_BUFFER_BIT);
GLfloat vRed[] = {1.0,1.00,0.0,0.5f};
shaderManager.UseStockShader(GLT_SHADER_IDENTITY,vRed);
triangleBatch.Draw();
glutSwapBuffers();
}
(6)消息循环--窗口大小改变
void changeSize(int w,int h)
{
glViewport(0, 0, w, h);
}
三、绘制正方形并使用键位控制
正方形.jpeg
代码如下：
(1) 引入头文件
#include "GLShaderManager.h"
#include "GLTools.h"
#include <GLUT/GLUT.h>
(2)定义工具类对象（着色器管理类、三角形批次类）、正方形边长和四个点坐标
GLShaderManager shaderManager;
GLBatch triangleBatch;
// 边长
GLfloat blockSize = 0.1f;
//正方形的4个点坐标
GLfloat vVerts[] = {
-blockSize,-blockSize,0.0f,
blockSize,-blockSize,0.0f,
blockSize,blockSize,0.0f,
-blockSize,blockSize,0.0f
};
(3)入口函数Main（初始化）
int main(int argc,char *argv[])
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGBA|GLUT_DEPTH|GLUT_STENCIL);
glutInitWindowSize(800, 600);
glutCreateWindow("Triangle");
glutReshapeFunc(changeSize);
glutDisplayFunc(RenderScene);
//注册特殊函数
glutSpecialFunc(SpecialKeys);
GLenum status = glewInit();
if (GLEW_OK != status) {
printf("GLEW Error:%s\n",glewGetErrorString(status));
return 1;
}
setupRC();
glutMainLoop();
return 0;
}
(4)初始化setupRC
void setupRC()
{
glClearColor(0.98f, 0.40f, 0.7f, 1);
shaderManager.InitializeStockShaders();
//修改为GL_TRIANGLE_FAN ，4个顶点
triangleBatch.Begin(GL_TRIANGLE_FAN, 4);
triangleBatch.CopyVertexData3f(vVerts);
triangleBatch.End();
}
(5)消息循环--渲染回调
void RenderScene(void)
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT|GL_STENCIL_BUFFER_BIT);
GLfloat vRed[] = {1.0,1.00,0.0,0.5f};
shaderManager.UseStockShader(GLT_SHADER_IDENTITY,vRed);
triangleBatch.Draw();
glutSwapBuffers();
}
(6)消息循环--窗口大小改变
void changeSize(int w,int h)
{
glViewport(0, 0, w, h);
}
（7）SpecialKeys
第一种方式：改变顶点坐标
void SpecialKeys(int key, int x, int y){
GLfloat stepSize = 0.025f;
GLfloat blockX = vVerts[0];
GLfloat blockY = vVerts[10];
if (key == GLUT_KEY_UP) {
blockY += stepSize;
}
if (key == GLUT_KEY_DOWN) {
blockY -= stepSize;
}
if (key == GLUT_KEY_LEFT) {
blockX -= stepSize;
}
if (key == GLUT_KEY_RIGHT) {
blockX += stepSize;
}
//触碰到边界（4个边界）的处理
//当正方形移动超过最左边的时候
if (blockX < -1.0f) {
blockX = -1.0f;
}
//当正方形移动到最右边时
//1.0 - blockSize * 2 = 总边长 - 正方形的边长 = 最左边点的位置
if (blockX > (1.0 - blockSize * 2)) {
blockX = 1.0f - blockSize * 2;
}
//当正方形移动到最下面时
//-1.0 - blockSize * 2 = Y（负轴边界） - 正方形边长 = 最下面点的位置
if (blockY < -1.0f + blockSize * 2 ) {
blockY = -1.0f + blockSize * 2;
}
//当正方形移动到最上面时
if (blockY > 1.0f) {
blockY = 1.0f;
}
// Recalculate vertex positions
vVerts[0] = blockX;
vVerts[1] = blockY - blockSize*2;
vVerts[3] = blockX + blockSize*2;
vVerts[4] = blockY - blockSize*2;
vVerts[6] = blockX + blockSize*2;
vVerts[7] = blockY;
vVerts[9] = blockX;
vVerts[10] = blockY;
triangleBatch.CopyVertexData3f(vVerts);
glutPostRedisplay();
}
第二种方式：改变顶点着色器的矩阵
void RenderScene(void)
{
//清缓存区
glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT|GL_STENCIL_BUFFER_BIT);
GLfloat vRed[] = {1.0f,0.0f,0.0f,0.0f};
M3DMatrix44f mFinalTransform,mTransfromMatrix,mRotationMartix;
//平移
m3dTranslationMatrix44(mTransfromMatrix, xPos, yPos, 0.0f);
//每次平移时，旋转5度
static float yRot = 0.0f;
yRot += 5.0f;
m3dRotationMatrix44(mRotationMartix, m3dDegToRad(yRot), 0.0f, 0.0f, 1.0f);
//将旋转和移动的矩阵结果 合并到mFinalTransform （矩阵相乘）
m3dMatrixMultiply44(mFinalTransform, mTransfromMatrix, mRotationMartix);
//将矩阵结果 提交给固定着色器（平面着色器）中绘制
shaderManager.UseStockShader(GLT_SHADER_FLAT,mFinalTransform,vRed);
triangleBatch.Draw();
//执行交换缓存区
glutSwapBuffers();
}
