Thought I’d have a go using the Normal Map code from the last post to do some bump-mapping.
Turns out it’s quite easy to use the output of the Normal Map CIFilter as normals in a Fragment Shader. All that needs to be done is to transform it into the correct range by multiplying the RGB value of each pixel by 2.0, then subtracting 1.0.
Some examples using a simple Phong lighting model, and normals extracted from first a static image, then the live video from the iSight camera, run through the Normal Map CIFilter:
Here’s the GLSL code:
Vertex Shader:
varying vec3 normal, lightDir, eyeVec;
void main()
{
// Normal from mesh
normal = gl_NormalMatrix * gl_Normal;
// Current Vertex coordinates transformed into World space
vec3 Vertex = vec3(gl_ModelViewMatrix * gl_Vertex);
// Light Direction
lightDir = vec3(gl_LightSource[0].position.xyz - Vertex);
// Eye Vector
eyeVec = -Vertex;
gl_Position = ftransform();
gl_FrontColor = gl_Color;
gl_TexCoord[0] = gl_TextureMatrix[0] * gl_MultiTexCoord0;
}
Fragment Shader:
varying vec3 normal, lightDir, eyeVec;
uniform sampler2D texture;
uniform sampler2D normalMap;
void main (void)
{
// Base color
vec4 final_color =
(gl_FrontLightModelProduct.sceneColor * gl_FrontMaterial.ambient) +
(gl_LightSource[0].ambient * gl_FrontMaterial.ambient);
vec3 N = texture2D(normalMap, gl_TexCoord[0].st).rgb * 2.0 - 1.0;
//vec3 N = normalize(normal); // Normal
vec3 L = normalize(lightDir); // Light Direction (normalized)
float lambertTerm = dot(N,L); // Base lighting (no ambient or specular contribution)
if(lambertTerm > 0.0)
{
// Add diffuse contribution
final_color += gl_LightSource[0].diffuse * gl_FrontMaterial.diffuse * lambertTerm;
// Compute specular contribution
vec3 E = normalize(eyeVec);
vec3 R = reflect(-L, N);
float specular = pow(max(dot(R, E), 0.0), gl_FrontMaterial.shininess);
// Add specular contribution
final_color += gl_LightSource[0].specular * gl_FrontMaterial.specular * specular;
}
// Output
gl_FragColor = final_color;// * texture2D(texture, gl_TexCoord[0].xy);
}
Note
You’ll need to stick the GLSL shader inside a Lighting Patch in order to be able to set the properties for the light.
You’ll get an error in the Frag shader about the varying normal not being used.
