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zf223669
09-23-2005, 02:02 AM
the code is like that:
void display(void)
{
GLfloat position[] = { 0.0, 0.0, 1.5, 1.0 };

glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glPushMatrix ();
gluLookAt (0.0, 0.0, 5.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);

glPushMatrix ();
glRotated ((GLdouble) spin, 1.0, 1.0, 0.0);
//glTranslated(0.0,0.0,z);
glLightfv (GL_LIGHT0, GL_POSITION, position);
glLightf(GL_LIGHT0,GL_CONSTANT_ATTENUATION,1.2);
glLightf(GL_LIGHT0,GL_LINEAR_ATTENUATION,0.5);

glTranslated (0.0, 0.0, 1.5);
glDisable (GL_LIGHTING);
//////////////////////////////////////////////
here,why shut off the light
//////////////////////////////////////////////
glColor3f (0.0, 1.0, 1.0);
glutWireCube (0.1);
glEnable (GL_LIGHTING);
glPopMatrix ();

glutSolidTorus (0.275, 0.85, 30, 30);
glPopMatrix ();
glFlush ();
}

void reshape (int w, int h)
{
glViewport (0, 0, (GLsizei) w, (GLsizei) h);
glMatrixMode (GL_PROJECTION);
glLoadIdentity();
gluPerspective(40.0, (GLfloat) w/(GLfloat) h, 1.0, 20.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}

void mouse(int button, int state, int x, int y)
{
switch (button) {
case GLUT_LEFT_BUTTON:
if (state == GLUT_DOWN) {
spin = (spin + 30) % 360;
//z = (z + 1) % 40;
glutPostRedisplay();
}
break;
default:
break;
}
}

void keyboard(unsigned char key, int x, int y)
{
switch (key) {
case 27:
exit(0);
break;
}
}

int main(int argc, char** argv)
{
glutInit(&argc, argv);
glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);
glutInitWindowSize (500, 500);
glutInitWindowPosition (100, 100);
glutCreateWindow (argv[0]);
init ();
glutDisplayFunc(display);
glutReshapeFunc(reshape);
glutMouseFunc(mouse);
glutKeyboardFunc(keyboard);
glutMainLoop();
return 0;
}
thank you ....

tamlin
09-23-2005, 02:43 AM
Because the author of that code didn't want to have the wireframe cube lit? :)

Compare the coordinates of the light itself, and the translate call before drawing the wireframe cube. Then think "light falloff". After that, I think everything should be clear.

zf223669
09-24-2005, 06:43 PM
THANK YOU VERY MUSH :)