Week05

Light












#include <GL/glut.h>

///打光的第0步，宣告陣列，裡面有光的屬性值
const GLfloat light_ambient[]  = { 0.0f, 0.0f, 0.0f, 1.0f };
const GLfloat light_diffuse[]  = { 1.0f, 1.0f, 1.0f, 1.0f };
const GLfloat light_specular[] = { 1.0f, 1.0f, 1.0f, 1.0f };
const GLfloat light_position[] = { 5.0f, 5.0f, -5.0f, 0.0f };

const GLfloat mat_ambient[]    = { 0.7f, 0.7f, 0.7f, 1.0f };
const GLfloat mat_diffuse[]    = { 0.8f, 0.8f, 0.8f, 1.0f };
const GLfloat mat_specular[]   = { 1.0f, 1.0f, 1.0f, 1.0f };
const GLfloat high_shininess[] = { 100.0f };

void display()
{
    glColor3ub(255,255,255);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glutSolidTeapot(0.5);
    glutSwapBuffers();
}

///控制光線移動
void motion(int x,int y)
{
    GLfloat light_position[] = {5.0f, 5.0f, -5.0f, 0.0f};
    light_position[0] = (x-250)/250.0 * 10;
    light_position[1] = -(y-250)/250.0 * 10;
    glLightfv(GL_LIGHT0, GL_POSITION, light_position);
    glutPostRedisplay();
}

int main(int argc,char *argv[])
{
    glutInit(&argc, argv);
    glutInitWindowSize(500,500);
    glutInitWindowPosition(750,250);
    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
    glutCreateWindow("GLUT Shapes");
    glutDisplayFunc(display);
    glutMotionFunc(motion);

    ///打光也需要 3D的 Depth Test
    glEnable(GL_DEPTH_TEST);

    ///打光1：要開啟光線，原來範例就寫好了
    glEnable(GL_LIGHT0);
    glEnable(GL_NORMALIZE);
    glEnable(GL_COLOR_MATERIAL);
    glEnable(GL_LIGHTING);

    ///打光2：要設定光Light的設定值 （前面有陣列，這裡拿來用）
    glLightfv(GL_LIGHT0, GL_AMBIENT,  light_ambient);
    glLightfv(GL_LIGHT0, GL_DIFFUSE,  light_diffuse);
    glLightfv(GL_LIGHT0, GL_SPECULAR, light_specular);
    glLightfv(GL_LIGHT0, GL_POSITION, light_position);

    ///打光2.2：要把物體也設定好它的Material
    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);
    ///其實原本177行程裡，已經有打光需要的程式了
    glutMainLoop();

    return EXIT_SUCCESS;
}