openGL 灯光与材质例子. 顺带完成了一个颇复杂的平面分级算法, 修正版,列出了所有易错的地方:
1. 开启了 GL_XXX_ARRAY 后一定要使用对应的pointer, 否则就把 GL_XXX_ARRAY disable 掉.
2. 法线不一定要设置, openGL会自动为每一Vertex生成一个默认的, 自己设置当然可控性更好.
3. initLights() 等GL具体到场景内容的设置必须放在 GLUT 基本设置之后(一开始就死在这个弱智的问题).
4. 灯光的 GL_POSITION, 齐次坐标最后一位如果是 0, 则为平行光, 无需设置 GL_SPOT_DIRECTION 和 GL_SPOT_CUTOFF(这个值为照射角的一半). 如果是1, 则为聚光灯.
5. GL 环境光对所有面都会有影响.尝试变换灯光的颜色和环境光颜色的数组值,观察其变化.
6. 材质的 SHINESS 参数, 1 端接近橡胶与织物, 128 端接近金属与清漆.
7. 灯灯灯凳~ 最麻烦的还是平面分级算法, 理论上分级越细, 关照效果越细致, 代码如下:
#include <gl/GLUT.h> #include <stdio.h> static GLfloat LEVEL=12; static GLfloat LENGTH=2; static GLfloat START_PT=-1*(LENGTH/2); static GLfloat END_PT=1*(LENGTH/2); GLfloat angle=0; GLfloat *vertices; //GLfloat *colors; short *indices; GLfloat *normals; //GLfloat vertices[]={-1,-1,1, // -0.3333f,-1,1, // 0.3333f,-1,1, // 1,-1,1, // -1,-0.3333,1, // -0.3333f,-0.3333,1, // 0.3333f,-0.3333,1, // 1,-0.3333,1, // -1,0.3333,1, // -0.3333f,0.3333,1, // 0.3333f,0.3333,1, // 1,0.3333,1, // -1,1,1, // -0.3333f,1,1, // 0.3333f,1,1, // 1,1,1}; //short indices[]={0,1,4, 1,5,4, 1,2,5, 2,6,5, 2,3,6, 3,7,6, // 4,5,8, 5,9,8, 5,6,9, 6,10,9, 6,7,10, 7,11,10, // 8,9,12, 9,13,12, 9,10,13, 10,14,13, 10,11,14, 11,15,14}; //lights GLfloat lightPos[]={0,0,2.5f,1}; GLfloat lightColor[]={0.6f,0.3f,0.3f,1}; //red GLfloat lightDir[]={0,0,-1}; //ambient light GLfloat light_ambient[]={0.3f,0.3f,0.4f,1}; //light blue //materials GLfloat cubeColor[]={0.6f,0.6f,0.6f,1}; //gray color GLfloat cubeSpecular[]={1,1,1,1}; void setMaterial(){ glMaterialfv(GL_FRONT_AND_BACK,GL_AMBIENT_AND_DIFFUSE,cubeColor); glMaterialfv(GL_FRONT_AND_BACK,GL_SPECULAR,cubeSpecular); //try to change the shiness from 1(rubber/frabic)-128(metal/clear painted) glMaterialf(GL_FRONT_AND_BACK,GL_SHININESS,20); } void drawPlane(){ glVertexPointer(3,GL_FLOAT,0,vertices); //glNormalPointer(GL_FLOAT,0,normals); //glColorPointer(4,GL_FLOAT,0,colors); glDrawElements(GL_TRIANGLES,(GLsizei)((LEVEL-1)*(LEVEL-1)*2*3),GL_UNSIGNED_SHORT,indices); } void drawCube(){ //set material setMaterial(); glPushMatrix(); drawPlane(); glPopMatrix(); glPushMatrix(); glRotatef(-90,1,0,0); drawPlane(); glPopMatrix(); glPushMatrix(); glRotatef(90,1,0,0); drawPlane(); glPopMatrix(); glPushMatrix(); glRotatef(180,1,0,0); drawPlane(); glPopMatrix(); glPushMatrix(); glRotatef(90,0,1,0); drawPlane(); glPopMatrix(); glPushMatrix(); glRotatef(-90,0,1,0); drawPlane(); glPopMatrix(); } void rendering(void){ glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT); glPushMatrix(); glRotatef(angle,0,1,0); drawCube(); glPopMatrix(); glutSwapBuffers(); angle+=0.01; } void reshape(int w, int h){ if(h==0){ h=1; } GLfloat ratio=(GLfloat)(w/h); glMatrixMode(GL_PROJECTION); glLoadIdentity(); glViewport(0,0,w,h); gluPerspective(45,ratio,0.1,1000); gluLookAt(0,5,10,0,0,0,0,1,0); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); } void makeArrays(){ //build vertices array for one face GLfloat step=(GLfloat)(LENGTH/(LEVEL-1)); GLint total=LEVEL*LEVEL*3; GLint oneLine=LEVEL*3; //12 //printf("level: %f ", step); vertices=new GLfloat[total]; for(int i=0;i<LEVEL;i++){ //every point x,y,z for(int j=0;j<LEVEL*3;j+=3){ vertices[(i*oneLine)+j]=(GLfloat)(START_PT+(j*step/3)); vertices[(i*oneLine)+(j+1)]=(GLfloat)(START_PT+i*step); vertices[(i*oneLine)+(j+2)]=(GLfloat)(LENGTH/2); printf("pt : x: %f, y: %f, z: %f \n", vertices[(i*oneLine)+j], vertices[(i*oneLine)+j+1], vertices[(i*oneLine)+j+2]); } } //build colors array, normal white color; /*GLint totalColor=LEVEL*LEVEL*4; colors=new GLfloat[totalColor]; for(int r=0;r<totalColor;r+=4){ colors[r]=1; colors[r+1]=1; colors[r+2]=1; colors[r+3]=1; }*/ //build index array for one face //using TRIANGLES indices=new short[(LEVEL-1)*(LEVEL-1)*2*3]; //square of LEVEL-1, 2 triangles, 3 points; for(int m=0;m<LEVEL-1;m++){ for(int n=0;n<LEVEL-1;n++){ indices[m*((GLint)LEVEL-1)*6+n*6+0]=n+m*((GLint)LEVEL-1)+m+0; indices[m*((GLint)LEVEL-1)*6+n*6+1]=n+m*((GLint)LEVEL-1)+m+1; indices[m*((GLint)LEVEL-1)*6+n*6+2]=n+m*((GLint)LEVEL-1)+m+(LEVEL); indices[m*((GLint)LEVEL-1)*6+n*6+3]=n+m*((GLint)LEVEL-1)+m+1; indices[m*((GLint)LEVEL-1)*6+n*6+4]=n+m*((GLint)LEVEL-1)+m+(LEVEL)+1; indices[m*((GLint)LEVEL-1)*6+n*6+5]=n+m*((GLint)LEVEL-1)+m+(LEVEL); } } normals=new GLfloat[LEVEL*LEVEL*3]; for(int s=0;s<LEVEL*LEVEL*3;s+=3){ normals[s]=0; normals[s+1]=0; normals[s+2]=1; } } void initLights(){ glEnable(GL_LIGHTING); glEnable(GL_LIGHT0); glLightfv(GL_LIGHT0,GL_POSITION,lightPos); glLightfv(GL_LIGHT0,GL_AMBIENT,lightColor); glLightfv(GL_LIGHT0,GL_DIFFUSE,lightColor); glLightfv(GL_LIGHT0,GL_SPECULAR,lightColor); glLightfv(GL_LIGHT0,GL_SPOT_DIRECTION,lightDir); glLightf(GL_LIGHT0,GL_SPOT_CUTOFF,45); // glLightModelfv(GL_LIGHT_MODEL_AMBIENT,light_ambient); } int main(int argc, char* args[]){ //make arrays makeArrays(); //basic init glutInit(&argc,args); glutInitDisplayMode(GLUT_RGBA | GLUT_DEPTH | GLUT_DOUBLE); //window init glutInitWindowPosition(100,100); glutInitWindowSize(600,600); glutCreateWindow("light cube"); //functions init glutDisplayFunc(rendering); glutIdleFunc(rendering); glutReshapeFunc(reshape); //gl init glEnable(GL_DEPTH_TEST); glEnableClientState(GL_VERTEX_ARRAY); //glEnableClientState(GL_NORMAL_ARRAY); //glEnableClientState(GL_COLOR_ARRAY); glPolygonMode(GL_FRONT_AND_BACK,GL_FILL); //init lights initLights(); //run main loop, trigger all the funtions glutMainLoop(); return 0; }