phongShading.lua

teapot = Transform{Sphere{}}
RelativeTo.World:addChild(teapot)

applyPhongToStateSet = function(stateset)
    local vert = osg.Shader(osg.Shader.Type.VERTEX, [[
        varying vec3 N;
        varying vec3 v;
        void main(void)  
        {     
           v = vec3(gl_ModelViewMatrix * gl_Vertex);       
           N = normalize(gl_NormalMatrix * gl_Normal);
           gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;  
        }
    ]])
 
    local frag = osg.Shader(osg.Shader.Type.FRAGMENT, [[
        varying vec3 N;
        varying vec3 v;    
        void main (void)  
        {  
           vec3 L = normalize(gl_LightSource[0].position.xyz - v);   
           vec3 E = normalize(-v); // we are in Eye Coordinates, so EyePos is (0,0,0)  
           vec3 R = normalize(-reflect(L,N));  
         
           //calculate Ambient Term:  
           vec4 Iamb = gl_FrontLightProduct[0].ambient;    
 
           //calculate Diffuse Term:  
           vec4 Idiff = gl_FrontLightProduct[0].diffuse * max(dot(N,L), 0.0);
           Idiff = clamp(Idiff, 0.0, 1.0);     
           
           // calculate Specular Term:
           vec4 Ispec = gl_FrontLightProduct[0].specular 
                        * pow(max(dot(R,E),0.0),0.3*gl_FrontMaterial.shininess);
           Ispec = clamp(Ispec, 0.0, 1.0); 
           // write Total Color:  
           gl_FragColor = gl_FrontLightModelProduct.sceneColor + Iamb + Idiff + Ispec;     
        }
    ]])
 
    local program = osg.Program()
    program:addShader(vert)
    program:addShader(frag)
    stateset:setAttributeAndModes(program, osg.StateAttribute.Values.ON)
end
 
 
applyPhongToStateSet(teapot:getOrCreateStateSet())