这篇文章主要介绍深度测试和正背面剔除,主要代码就是以下几行。
深度测试+正背面剔除.gif核心代码:
glEnable(GL_CULL_FACE); //开启剔除
glFrontFace(GL_CCW); //设置逆时针为正面
glCullFace(GL_BACK); //剔除背面
glDisable(GL_CULL_FACE); //关闭剔除
glEnable(GL_DEPTH_TEST); //开启深度测试
glDisable(GL_DEPTH_TEST); //关闭深度测试
一. 设置成员变量
////设置角色帧,作为相机
GLFrame viewFrame;
//使用GLFrustum类来设置透视投影
GLFrustum viewFrustum;
GLTriangleBatch torusBatch;
GLMatrixStack modelViewMatix;
GLMatrixStack projectionMatrix;
GLGeometryTransform transformPipeline;
GLShaderManager shaderManager;
//标记:背面剔除、深度测试
int iCull = 0;
int iDepth = 0;
一. 右键菜单栏选项
void ProcessMenu(int value)
{
switch(value)
{
case 1:
iDepth = !iDepth;
break;
case 2:
iCull = !iCull;
break;
case 3:
glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
break;
case 4:
glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
break;
case 5:
glPolygonMode(GL_FRONT_AND_BACK, GL_POINT);
break;
}
glutPostRedisplay();
}
二. 召唤场景
void RenderScene(void)
{
//清除窗口和深度缓冲区
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
//根据设置iCull标记来判断是否开启背面剔除
if(iCull)
{
glEnable(GL_CULL_FACE);
glFrontFace(GL_CCW);
glCullFace(GL_BACK);
}
else
glDisable(GL_CULL_FACE);
//根据设置iDepth标记来判断是否开启深度测试
if(iDepth)
glEnable(GL_DEPTH_TEST);
else
glDisable(GL_DEPTH_TEST);
//把摄像机矩阵压入模型矩阵中
modelViewMatix.PushMatrix(viewFrame);
GLfloat vRed[] = { 1.0f, 0.0f, 0.0f, 1.0f };
//使用平面着色器
//参数1:平面着色器
//参数2:模型视图投影矩阵
//参数3:颜色
//shaderManager.UseStockShader(GLT_SHADER_FLAT, transformPipeline.GetModelViewProjectionMatrix(), vRed);
//使用默认光源着色器
//通过光源、阴影效果跟提现立体效果
//参数1:GLT_SHADER_DEFAULT_LIGHT 默认光源着色器
//参数2:模型视图矩阵
//参数3:投影矩阵
//参数4:基本颜色值
shaderManager.UseStockShader(GLT_SHADER_DEFAULT_LIGHT, transformPipeline.GetModelViewMatrix(), transformPipeline.GetProjectionMatrix(), vRed);
//绘制
torusBatch.Draw();
//出栈
modelViewMatix.PopMatrix();
glutSwapBuffers();
}
三. context. 图像上下文
void SetupRC()
{
// 设置背景颜色
glClearColor(0.3f, 0.3f, 0.3f, 1.0f );
//初始化着色器管理器
shaderManager.InitializeStockShaders();
//将相机向后移动7个单元:肉眼到物体之间的距离
viewFrame.MoveForward(7.0);
//创建一个甜甜圈
//void gltMakeTorus(GLTriangleBatch& torusBatch, GLfloat majorRadius, GLfloat minorRadius, GLint numMajor, GLint numMinor);
//参数1:GLTriangleBatch 容器帮助类
//参数2:外边缘半径
//参数3:内边缘半径
//参数4、5:主半径和从半径的细分单元数量
gltMakeTorus(torusBatch, 1.0f, 0.3f, 52, 26);
//点的大小
glPointSize(4.0f);
}
四. 键位设置,通过不同的键位对其进行设置,控制Camera的移动,从而改变视口
void SpecialKeys(int key, int x, int y)
{
if(key == GLUT_KEY_UP)
viewFrame.RotateWorld(m3dDegToRad(-5.0), 1.0f, 0.0f, 0.0f);
if(key == GLUT_KEY_DOWN)
viewFrame.RotateWorld(m3dDegToRad(5.0), 1.0f, 0.0f, 0.0f);
if(key == GLUT_KEY_LEFT)
viewFrame.RotateWorld(m3dDegToRad(-5.0), 0.0f, 1.0f, 0.0f);
if(key == GLUT_KEY_RIGHT)
viewFrame.RotateWorld(m3dDegToRad(5.0), 0.0f, 1.0f, 0.0f);
//重新刷新window
glutPostRedisplay();
}
五. 修改窗口大小
void ChangeSize(int w, int h)
{
//防止h变为0
if(h == 0)
h = 1;
//设置视口窗口尺寸
glViewport(0, 0, w, h);
//setPerspective函数的参数是一个从顶点方向看去的视场角度(用角度值表示)
// 设置透视模式,初始化其透视矩阵
viewFrustum.SetPerspective(35.0f, float(w)/float(h), 1.0f, 100.0f);
//把透视矩阵加载到透视矩阵对阵中
projectionMatrix.LoadMatrix(viewFrustum.GetProjectionMatrix());
// 初始化渲染管线
transformPipeline.SetMatrixStacks(modelViewMatix, projectionMatrix);
}
六. 初始化
int main(int argc, char* argv[])
{
gltSetWorkingDirectory(argv[0]);
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA | GLUT_DEPTH | GLUT_STENCIL);
glutInitWindowSize(800, 600);
glutCreateWindow("Geometry Test Program");
glutReshapeFunc(ChangeSize);
glutSpecialFunc(SpecialKeys);
glutDisplayFunc(RenderScene);
// Create the Menu
glutCreateMenu(ProcessMenu);
glutAddMenuEntry("Toggle depth test",1);
glutAddMenuEntry("Toggle cull backface",2);
glutAddMenuEntry("Set Fill Mode", 3);
glutAddMenuEntry("Set Line Mode", 4);
glutAddMenuEntry("Set Point Mode", 5);
glutAttachMenu(GLUT_RIGHT_BUTTON);
GLenum err = glewInit();
if (GLEW_OK != err) {
fprintf(stderr, "GLEW Error: %s\n", glewGetErrorString(err));
return 1;
}
SetupRC();
glutMainLoop();
return 0;
}
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