shader() example

This shader implements the gazing ball reflection mapping discussed in class and shown above.

void
shader(float *color)
{
    int iu,iv;

    /* Compute texture coordinates given the surface normal */
    
    iu = 0.5 * (surfaceNormal[0] + 1) * theTexture->width;
    iv = 0.5 * (surfaceNormal[1] + 1) * theTexture->height;

    /* Get color from texture */
    
    if ((iu >= 0) && (iu < theTexture->width) &&
	(iv >= 0) && (iv < theTexture->height)) {
	Pixel pixel = ImagePixel(theTexture, iu, iv);
	vec_set(color, pixel.r / 255.0, pixel.g / 255.0, pixel.b / 255.0);
    }
    else
	vec_set(color, 0, 0, 0);
}

The following .cfg 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 10
int   numLights = 1
#
# Shader variables go here
#
string whichShader = reflection
string textureName = images/cafe.ppm