shader() example

This shader will illuminate a surface with a directional light. It assumes that the lightNDir parameters have been set for each light.

void
shader(float *color)
{
  int i;
  
  vec_set(color,0,0,0);  
  for(i=0 ; i<numLights ; i++)
  {
    float tmp[3];
    float dot = -vec_dot(lights[i].direction,surfaceNormal);
    
    vec_scale2(dot,lights[i].color,tmp);
    vec_comp_mult(tmp,diffuseColor,tmp);
    vec_add(tmp,color,color);
  }
  vec_clamp(color, 0, 1);
}

The following configuration file could be used with this shader:

#
# This stuff has nothing to do with the shader, only scene layout
#
string patchObject = models/patches/teapot.obj
int   loDice = 10
int   hiDice = 20
int   zNear = 10
float fieldOfView = 90
vec   eyePosition = 0 0 20
int   numLights = 2
vec   light0Pos = 0 20 40
color light0Color = 1 0 0
vec   light1Pos = 0 -20 40
color light1Color = 0 1 0
#
# Shader variables go here
#
color diffuseColor = 0.5 0.5 0.5
string whichShader = directional