OpenGL - Ambient light working in simulator, not on device.

[jshmrsn]

My implementation of OpenGL displays ambient light normally while running in the iPhone OS simulator, but acts as if ambient light color was 0,0,0 on the device.

I activate lighting like so:


glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);

GLfloat ambient[] = {0.6, 0.6, 0.6, 1.0 };
GLfloat diffuse[] = { 1, 1, 1, 1 };
GLfloat specular[] = { 0,0, 0, 1.0 };

glLightfv(GL_LIGHT0, GL_AMBIENT, ambient);
glLightfv(GL_LIGHT0, GL_DIFFUSE, diffuse);
glLightfv( GL_LIGHT0, GL_SPECULAR, specular);

GLfloat position[] = { direction.x, direction.y, direction.z, 0.0 };
glLightfv(GL_LIGHT0, GL_POSITION, position);



GLfloat amb[] = { 1,1, 1, 1.0 };
GLfloat diffuse[] = { 1, 1, 1, 1.0 };
glMaterialfv(GL_FRONT, GL_AMBIENT, amb);
glMaterialfv(GL_FRONT, GL_DIFFUSE, diffuse);


Working...

http://img213.imageshack.us/img213/1002/96233945kc6.th.jpg (http://img213.imageshack.us/my.php?image=96233945kc6.jpg)http://img213.imageshack.us/images/thpix.gif (http://g.imageshack.us/thpix.php)

Not working...

http://img510.imageshack.us/img510/5461/20435449it6.th.jpg (http://img510.imageshack.us/my.php?image=20435449it6.jpg)http://img510.imageshack.us/images/thpix.gif (http://g.imageshack.us/thpix.php)


Thanks for any help/ideas.

-Josh Rosen

[SqueegyX]

I have seen this exact same thing. Is the iphone incapable of ambient light in lighting rendering? That seems like it would be crazy.

[jshmrsn]

Well I'm not exactly sure what fixed it, but by strictly following this tutorial I was able to get ambient lighting to work.

http://www.zeuscmd.com/tutorials/opengles/15-Lighting.php

my code is now:


float lightAmbient[] = { 0.3f, 0.3f, 0.3f, 1.0f };
float lightDiffuse[] = { 1.0f, 1.0f, 1.0f, 1.0f };

float matAmbient[] = { 0.6f, 0.6f, 0.6f, 1.0f };
float matDiffuse[] = { 0.6f, 0.6f, 0.6f, 1.0f };

glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);

glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT, matAmbient);
glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, matDiffuse);

glLightfv(GL_LIGHT0, GL_AMBIENT, lightAmbient);
glLightfv(GL_LIGHT0, GL_DIFFUSE, lightDiffuse);


//using my vector class
direction.unit();
GLfloat position[] = { direction.x, direction.y, direction.z, 0.0 };
glLightfv(GL_LIGHT0, GL_POSITION, position);

[SqueegyX]

I think its the GL_FRONT_AND_BACK that makes it work. I used to just have GL_FRONT.

[jshmrsn]

Ah, good catch.

So problem solved I guess, cool.

[Frogblast]

If you had been checking for errors, an OpenGL ES implementation should reject the GL_FRONT value with a GL_INVALID_ENUM error.

Always use glGetError() to debug these kind of problems.

[SqueegyX]

Yeah but its weird because it works great because it works great in the simulator. Is the simulator OpenGL, not OpenGLES?

[robbieduncan]

Yeah but its weird because it works great because it works great in the simulator. Is the simulator OpenGL, not OpenGLES?

Lots of things work in the simulator that don't work on a real device. This is because the simulator has access to the full-on Mac OSX libraries rather than the limited Mobile OSX ones...