OpenGL中光照的设置

1.创建、定位和启用光源

(1)定义光源的颜色和位置

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

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

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

(2)创建光源

glLightfv(GL_LIGHT1, GL_AMBIENT, ambient);  // Setup The Ambient Light设置环境光

glLightfv(GL_LIGHT1, GL_DIFFUSE, diffuse);  // Setup The Diffuse Light设置漫射光

glLightfv(GL_LIGHT1, GL_POSITION,position);  // Position The Light设置光源位置

(3)启动光照和光源

glEnable(GL_LIGHTING);     // 启动光照

glEnable(GL_LIGHT1);     // Enable Light One启用一号光源

2.选择光照模型

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

GLfloat local_view[] = { 0.0 };

glLightModelfv(GL_LIGHT_MODEL_AMBIENT, lmodel_ambient);

glLightModelfv(GL_LIGHT_MODEL_LOCAL_VIEWER, local_view);

3.定义材质

(1)材料属性

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};

(2)指定材料属性

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);

4.绘制物体

glutSolidSphere(1.0, 16, 16);

引用OpenGL编程指南中的例子:

void init(void)

{

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

GLfloat diffuse[] = { 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);

/* draw sphere in first row, first column

*  diffuse reflection only; no ambient or specular  

*/

  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();

/* draw sphere in first row, second column

*  diffuse and specular reflection; low shininess; no ambient

*/

  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();

/* draw sphere in first row, third column

*  diffuse and specular reflection; high shininess; no ambient

*/

  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();

/* draw sphere in first row, fourth column

*  diffuse reflection; emission; no ambient or specular reflection

*/

  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();

/* draw sphere in second row, first column

*  ambient and diffuse reflection; no specular  

*/

  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();

/* draw sphere in second row, second column

*  ambient, diffuse and specular reflection; low shininess

*/

  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();

/* draw sphere in second row, third column

*  ambient, diffuse and specular reflection; high shininess

*/

  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();

/* draw sphere in second row, fourth column

*  ambient and diffuse reflection; emission; no specular

*/

  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();

/* draw sphere in third row, first column

*  colored ambient and diffuse reflection; no specular  

*/

  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();

/* draw sphere in third row, second column

*  colored ambient, diffuse and specular reflection; low shininess

*/

  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();

/* draw sphere in third row, third column

*  colored ambient, diffuse and specular reflection; high shininess

*/

  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();

/* draw sphere in third row, fourth column

*  colored ambient and diffuse reflection; emission; no specular

*/

  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();

}

void reshape(int w, int h)

{

glViewport(0, 0, w, h);

glMatrixMode(GL_PROJECTION);

glLoadIdentity();

if (w <= (h * 2))

   glOrtho (-6.0, 6.0, -3.0*((GLfloat)h*2)/(GLfloat)w, 

      3.0*((GLfloat)h*2)/(GLfloat)w, -10.0, 10.0);

else

   glOrtho (-6.0*(GLfloat)w/((GLfloat)h*2), 

      6.0*(GLfloat)w/((GLfloat)h*2), -3.0, 3.0, -10.0, 10.0);

glMatrixMode(GL_MODELVIEW);

glLoadIdentity();

}

int main(int argc, char** argv)

{

glutInit(&argc, argv);

glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);

glutInitWindowSize (600, 450);

glutCreateWindow(argv[0]);

init();

glutReshapeFunc(reshape);

glutDisplayFunc(display);

glutKeyboardFunc (keyboard);

glutMainLoop();

return 0; 

}

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