weeeeek05

這次的目的是要利用燈光讓茶壺變立體
#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[] = { 2.0f, 5.0f, -5.0f, 0.0f }; 決定燈光從哪裡來

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 };

/* Program entry point */

void display()
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glutSolidTeapot(0.3);
    glutSwapBuffers();
}
int main(int argc, char *argv[])
{
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
    glutCreateWindow("GLUT Shapes");
    glutDisplayFunc(display);

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

目的 : 可以移動光源

增加motion函式

void motion(int x,int y)
{
    GLfloat light_position[]={2.0f,5.0f,-5.0,0.0f};
    light_position[0] = (x-150)/150.0 * 10;
    light_position[1] = -(y-150)/150.0 * 10;
    glLightfv(GL_LIGHT0,GL_POSITION,light_position);
    glutPostRedisplay();
}

在main函式內加入motion函式

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