Lightning - Help Me!!!

[lsdi]

This code its how I put lights in my terrain engine, the problem is that the terrain looks like a chess-board, b&w quads.

My calculation of normals its ok.

 
lights() its in REDRAW function too
 
void lightsgl(void)
{	
	lights();    
	glEnable(GL_LIGHT0);
	glEnable(GL_LIGHTING);
}
 
void lights(void)
{
	float ambience[4] = {0.3f, 0.3f, 0.3f, 1.0};		
	float diffuse[4] = {0.5f, 0.5f, 0.5f, 1.0};
	float g_LightPosition[4] = {0, 1, 0, 1};
	glLightfv( GL_LIGHT0, GL_AMBIENT,  ambience );		
	glLightfv( GL_LIGHT0, GL_DIFFUSE,  diffuse );	
	glLightfv( GL_LIGHT0, GL_POSITION, g_LightPosition ); 
}

[Askrlfg]

Are you sure for the normals?

[MPech]

I do agree, there is nothing wrong with your code here, it may be a problem of normals.

How do you build them ?

[lsdi]

My normal calcs: (based on triangles)

quad_vect Cross(quad_vect vVector1, quad_vect vVector2)
{
	quad_vect vNormal;																
	vNormal.x = ((vVector1.y * vVector2.z) - (vVector1.z * vVector2.y));
	vNormal.y = ((vVector1.z * vVector2.x) - (vVector1.x * vVector2.z));														
	vNormal.z = ((vVector1.x * vVector2.y) - (vVector1.y * vVector2.x));
	return vNormal;								
}
 
quad_vect Vector(quad_vect vPoint1, quad_vect vPoint2)
{
	quad_vect vVector = {0};							
	vVector.x = vPoint1.x - vPoint2.x;					
	vVector.y = vPoint1.y - vPoint2.y;					
	vVector.z = vPoint1.z - vPoint2.z;				
	return vVector;										
}
 
float Magnitude(quad_vect vNormal)
{
	return (float)sqrt( (vNormal.x * vNormal.x) + 
						(vNormal.y * vNormal.y) + 
						(vNormal.z * vNormal.z) );
}
 
quad_vect Normalize(quad_vect vNormal)
{
	float magnitude = Magnitude(vNormal);			
	vNormal.x /= magnitude;					
	vNormal.y /= magnitude;							
	vNormal.z /= magnitude;							
	return vNormal;									
}
 
quad_vect normal(quad_vect p0,quad_vect p1,quad_vect p2)				
{													
	quad_vect vVector1 = Vector(p2, p0);
	quad_vect vVector2 = Vector(p1, p0);
	quad_vect vNormal = Cross(vVector1, vVector2);
	vNormal = Normalize(vNormal);						
	return vNormal;										
}

[blood.angel]

Try glShadeModel(GL_FLAT);

I had a similar problem where quads lined up together had that checkerboard effect in a light. Even though my normals were correct.

[lsdi]

same problem

[Miguel_dup1]

Do the dark sqaures in you terrain look like they never get lit up even if you move around your terrain? Are there only two shades of color, like a white and a gray? Or there is a bit of a gray scale going on?
If you have a gray scale color going on, I would say you are simply computing the normals and not the average normals which gives the effect of smoothness...

[Miguel_dup1]

Well, I was just looking at your normalization code, when you are not computing average normals which gives the effect of smothness... This is prolly what you need to do...

[lsdi]

How to average the normals?

[blood.angel]

Are you sure you have all your triangles ordered the right way? Either all clockwise or anticlockwise?