Question

I am having trouble with OpenGL 1.1 lighting. My code works on the iPhone 4 but not the iPhone 3G. Everything appears unlit (flat colours). I don’t have a 3GS so I can’t find out if it works on that one or not.

Here is my lighting setup:

- (void)setupLighting
{
    const GLfloat           lightAmbient[] = {0.2, 0.2, 0.2, 1.0};
    const GLfloat           matAmbient[] = {0.6, 0.6, 0.6, 1.0};        
    const GLfloat           matDiffuse[] = {1.0, 1.0, 1.0, 1.0};            
    const GLfloat           matSpecular[] = {0.6, 0.6, 0.6, 0.1};       
    const GLfloat           lightPosition[] = {0.0, 0.0, 0.0, 0.0};         
    const GLfloat           lightShininess = 100.0;     
    glEnable(GL_LIGHTING);      
    glEnable(GL_LIGHT0);        
    glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT, matAmbient);        
    glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, matDiffuse);        
    glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, matSpecular);      
    glMaterialf(GL_FRONT_AND_BACK, GL_SHININESS, lightShininess);       
    glLightfv(GL_LIGHT0, GL_AMBIENT, lightAmbient);     
    glLightfv(GL_LIGHT0, GL_POSITION, lightPosition);                  
    glShadeModel(GL_SMOOTH);    
    NSLog(@"Lighting sorted");
}

I supply normal vectors and so on after that, which successfully renders on the newer iPhone… however, I would really like to support all three iPhones. (It also works on the iPad).

Answer 1

Heh, to answer my own question (and provide info for anyone else with the same problem) there was a problem with the light position being (0, 0, 0, 0). Setting it to (0, 0, -1.0, 0) fixed the problem and didn’t disturb the lighting conditions on the other devices. I still don’t quite understand what I’ve done here, but I’m just glad I can provide compatibility to iPhone 3Gs…