OpenGL光照和材质

转自：http://www.cnblogs.com/phinecos/archive/2007/09/19/899107.html

26）光照模型有4部分：全局环境光，近视点或远视点，双面光照，镜面反射颜色是否和环境颜色，散射颜色分开。要指定全局环境光，可以如下:

GLfloat ambient[] = {0.3,0.3,0.3,1.0};glLightModelfv(GL_LIGHT_MODEL_AMBIENT,ambient);

顶点的镜面反射亮度取决于该点的法线，顶点相对于光源的方向以及顶点相对于视点的方向。要使用近视点，可以这样：glLightModelfv(GL_LIGHT_MODEL_LOCAL_VIEWER,GL_TRUE);这就将视点放置在(0,0,0)处. glLightModelfv(GL_LIGHT_MODEL_TWO_SIDE,GL_TRUE)启用双面光照。典型的光照计算中，分别计算环境光，散射光，镜面反射光和发射光的贡献，然后进行叠加，而在这之后进行纹理映射的话，镜面反射区可能被覆盖，为了解决这个问题，可以glLightModelfv(GL_LIGHT_MODEL_COLOR_CONTROL,GL_SEPARATE_SPECULAR_COLOR); 这样，每个顶点光照计算将产生两种颜色，主颜色和辅助颜色，前者包含所以非镜面反射光照的贡献，后者是所以镜面反射光照的总贡献。纹理映射的时候只将主颜色和纹理颜色混合起来，执行万纹理映射后，再将主颜色和纹理颜色的混合结果与辅助颜色混合起来。

27) 不同材质属性的示例：

OpenGL光照和材质

void init( void)

{

GLfloat ambient[] = { 1.0, 0.0, 0.0, 1.0 };

GLfloat diffuse[] = { 1.0, 1.0, 1.0, 1.0 };

GLfloat specular[] = { 1.0, 1.0, 1.0, 1.0 };

GLfloat position[] = { 0.0, 3.0, 2.0, 0.0 };

GLfloat lmodel_ambient[] = { 0.4, 0.4, 0.4, 1.0 };

GLfloat local_view[] = { 0.0 };

glClearColor(0.0, 0.1, 0.1, 0.0);

glEnable(GL_DEPTH_TEST);

glShadeModel(GL_SMOOTH);

glLightfv(GL_LIGHT0, GL_AMBIENT, ambient);

glLightfv(GL_LIGHT0, GL_DIFFUSE, diffuse);

glLightfv(GL_LIGHT0, GL_POSITION, position);

glLightModelfv(GL_LIGHT_MODEL_AMBIENT, lmodel_ambient);

glLightModelfv(GL_LIGHT_MODEL_LOCAL_VIEWER, local_view);

glEnable(GL_LIGHTING);

glEnable(GL_LIGHT0);

}

void display( void)

{

GLfloat no_mat[] = { 0.0, 0.0, 0.0, 1.0 };

GLfloat mat_ambient[] = { 0.7, 0.7, 0.7, 1.0 };

GLfloat mat_ambient_color[] = { 0.8, 0.8, 0.2, 1.0 };

GLfloat mat_diffuse[] = { 0.1, 0.5, 0.8, 1.0 };

GLfloat mat_specular[] = { 1.0, 1.0, 1.0, 1.0 };

GLfloat no_shininess[] = { 0.0 };

GLfloat low_shininess[] = { 5.0 };

GLfloat high_shininess[] = { 100.0 };

GLfloat mat_emission[] = {0.3, 0.2, 0.2, 0.0};

glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

glPushMatrix();

glTranslatef (-3.75, 3.0, 0.0);

glMaterialfv(GL_FRONT, GL_AMBIENT, no_mat);

glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_diffuse);

glMaterialfv(GL_FRONT, GL_SPECULAR, no_mat);

glMaterialfv(GL_FRONT, GL_SHININESS, no_shininess);

glMaterialfv(GL_FRONT, GL_EMISSION, no_mat);

glutSolidSphere(1.0, 16, 16);

glPopMatrix();

glPushMatrix();

glTranslatef (-1.25, 3.0, 0.0);

glMaterialfv(GL_FRONT, GL_AMBIENT, no_mat);

glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_diffuse);

glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular);

glMaterialfv(GL_FRONT, GL_SHININESS, low_shininess);

glMaterialfv(GL_FRONT, GL_EMISSION, no_mat);

glutSolidSphere(1.0, 16, 16);

glPopMatrix();

glPushMatrix();

glTranslatef (1.25, 3.0, 0.0);

glMaterialfv(GL_FRONT, GL_AMBIENT, no_mat);

glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_diffuse);

glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular);

glMaterialfv(GL_FRONT, GL_SHININESS, high_shininess);

glMaterialfv(GL_FRONT, GL_EMISSION, no_mat);

glutSolidSphere(1.0, 16, 16);

glPopMatrix();

glPushMatrix();

glTranslatef (3.75, 3.0, 0.0);

glMaterialfv(GL_FRONT, GL_AMBIENT, no_mat);

glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_diffuse);

glMaterialfv(GL_FRONT, GL_SPECULAR, no_mat);

glMaterialfv(GL_FRONT, GL_SHININESS, no_shininess);

glMaterialfv(GL_FRONT, GL_EMISSION, mat_emission);

glutSolidSphere(1.0, 16, 16);

glPopMatrix();

glPushMatrix();

glTranslatef (-3.75, 0.0, 0.0);

glMaterialfv(GL_FRONT, GL_AMBIENT, mat_ambient);

glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_diffuse);

glMaterialfv(GL_FRONT, GL_SPECULAR, no_mat);

glMaterialfv(GL_FRONT, GL_SHININESS, no_shininess);

glMaterialfv(GL_FRONT, GL_EMISSION, no_mat);

glutSolidSphere(1.0, 16, 16);

glPopMatrix();

glPushMatrix();

glTranslatef (-1.25, 0.0, 0.0);

glMaterialfv(GL_FRONT, GL_AMBIENT, mat_ambient);

glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_diffuse);

glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular);

glMaterialfv(GL_FRONT, GL_SHININESS, low_shininess);

glMaterialfv(GL_FRONT, GL_EMISSION, no_mat);

glutSolidSphere(1.0, 16, 16);

glPopMatrix();

glPushMatrix();

glTranslatef (1.25, 0.0, 0.0);

glMaterialfv(GL_FRONT, GL_AMBIENT, mat_ambient);

glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_diffuse);

glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular);

glMaterialfv(GL_FRONT, GL_SHININESS, high_shininess);

glMaterialfv(GL_FRONT, GL_EMISSION, no_mat);

glutSolidSphere(1.0, 16, 16);

glPopMatrix();

glPushMatrix();

glTranslatef (3.75, 0.0, 0.0);

glMaterialfv(GL_FRONT, GL_AMBIENT, mat_ambient);

glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_diffuse);

glMaterialfv(GL_FRONT, GL_SPECULAR, no_mat);

glMaterialfv(GL_FRONT, GL_SHININESS, no_shininess);

glMaterialfv(GL_FRONT, GL_EMISSION, mat_emission);

glutSolidSphere(1.0, 16, 16);

glPopMatrix();

glPushMatrix();

glTranslatef (-3.75, -3.0, 0.0);

glMaterialfv(GL_FRONT, GL_AMBIENT, mat_ambient_color);

glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_diffuse);

glMaterialfv(GL_FRONT, GL_SPECULAR, no_mat);

glMaterialfv(GL_FRONT, GL_SHININESS, no_shininess);

glMaterialfv(GL_FRONT, GL_EMISSION, no_mat);

glutSolidSphere(1.0, 16, 16);

glPopMatrix();

glPushMatrix();

glTranslatef (-1.25, -3.0, 0.0);

glMaterialfv(GL_FRONT, GL_AMBIENT, mat_ambient_color);

glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_diffuse);

glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular);

glMaterialfv(GL_FRONT, GL_SHININESS, low_shininess);

glMaterialfv(GL_FRONT, GL_EMISSION, no_mat);

glutSolidSphere(1.0, 16, 16);

glPopMatrix();

glPushMatrix();

glTranslatef (1.25, -3.0, 0.0);

glMaterialfv(GL_FRONT, GL_AMBIENT, mat_ambient_color);

glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_diffuse);

glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular);

glMaterialfv(GL_FRONT, GL_SHININESS, high_shininess);

glMaterialfv(GL_FRONT, GL_EMISSION, no_mat);

glutSolidSphere(1.0, 16, 16);

glPopMatrix();

glPushMatrix();

glTranslatef (3.75, -3.0, 0.0);

glMaterialfv(GL_FRONT, GL_AMBIENT, mat_ambient_color);

glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_diffuse);

glMaterialfv(GL_FRONT, GL_SPECULAR, no_mat);

glMaterialfv(GL_FRONT, GL_SHININESS, no_shininess);

glMaterialfv(GL_FRONT, GL_EMISSION, mat_emission);

glutSolidSphere(1.0, 16, 16);

glPopMatrix();

glFlush();

}

28）颜色材质模式，

glColorMaterial(GL_FRONT, GL_DIFFUSE);glEnable(GL_COLOR_MATERIAL);这将导致正面的DIFFUSE总是设置为当前颜色

29）混合时，首先指定源因子和目标因子，然后按照公式进行混合（默认的操作是相加），设置因子有两种方式：glBlenFunc()和glBlendFuncSeparate()（它可以指定4个因子，即可以使用不同的方式来混合RGB和alpha值）。除了默认的加法外，还可以使用glBlendEquation()来指定其他的混合方式（如减法等）。

30）启用反走样功能：glEnable(GL_POINT_SMOOTH)或glEnable (GL_LINE_SMOOTH);glEnable (GL_BLEND);或者采用glHint（），例如：

glEnable (GL_LINE_SMOOTH);

glEnable (GL_BLEND);

glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

glHint (GL_LINE_SMOOTH_HINT, GL_DONT_CARE);

31）雾的效果示例：

OpenGL光照和材质

static GLint fogMode;

static void init( void)

{

GLfloat position[] = { 0.5, 0.5, 3.0, 0.0 };

glEnable(GL_DEPTH_TEST);

glLightfv(GL_LIGHT0, GL_POSITION, position);

glEnable(GL_LIGHTING);

glEnable(GL_LIGHT0);

{

GLfloat mat[3] = {0.1745, 0.01175, 0.01175};

glMaterialfv (GL_FRONT, GL_AMBIENT, mat);

mat[0] = 0.61424; mat[1] = 0.04136; mat[2] = 0.04136;

glMaterialfv (GL_FRONT, GL_DIFFUSE, mat);

mat[0] = 0.727811; mat[1] = 0.626959; mat[2] = 0.626959;

glMaterialfv (GL_FRONT, GL_SPECULAR, mat);

glMaterialf (GL_FRONT, GL_SHININESS, 0.6*128.0);

}

glEnable(GL_FOG);

{

GLfloat fogColor[4] = {0.5, 0.5, 0.5, 1.0};

fogMode = GL_EXP;

glFogi (GL_FOG_MODE, fogMode);

glFogfv (GL_FOG_COLOR, fogColor);

glFogf (GL_FOG_DENSITY, 0.35);

glHint (GL_FOG_HINT, GL_DONT_CARE);

glFogf (GL_FOG_START, 1.0);

glFogf (GL_FOG_END, 5.0);

}

glClearColor(0.5, 0.5, 0.5, 1.0);

}

static void renderSphere (GLfloat x, GLfloat y, GLfloat z)

{

glPushMatrix();

glTranslatef (x, y, z);

glutSolidSphere(0.4, 16, 16);

glPopMatrix();

}

void display( void)

{

glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

renderSphere (-2., -0.5, -1.0);

renderSphere (-1., -0.5, -2.0);

renderSphere (0., -0.5, -3.0);

renderSphere (1., -0.5, -4.0);

renderSphere (2., -0.5, -5.0);

glFlush();

}

OpenGL光照和材质

继续阅读

一些java简写

真正意义上的“随机”---c语言

【OpenGL】粒子系统实例（三）

看看牛人们是怎么评价编程语言的

OpenGL编程指南2D部分【下】4. 颜色、像素和帧缓存5. 视图变换，剪切和反馈6. 纹理附1. 遇到的坑

Win7 下运行vc6.0 打开文件出现崩溃

bgfx跨平台渲染库学习笔记:概述

bgfx跨平台渲染库学习笔记:01-cubes绘制立方体

bgfx跨平台渲染库学习笔记:环境搭建

项目部分展示-3D在线试衣系统解决方案

UE4材质之图像处理颜色

UE4材质效果选中效果（物品或角色的边缘光）制作方法效果如下：

UE学习笔记：材质错乱排序函数

UE5_材质相关01（记录一下）

UE4中材质基于高度的颜色渐变

Babylon.js 第21章材质映射到网格+贴花