source: OGRE/trunk/ogrenew/Samples/Media/DeferredShadingMedia/DeferredShading/post/glsl/LightMaterial_ps.glsl @ 692

/******************************************************************************
Copyright (c) W.J. van der Laan

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/** Deferred shading framework
        // W.J. :wumpus: van der Laan 2005 //
        
        Post shader: Light geometry material
*/
uniform sampler2D tex0;
uniform sampler2D tex1;

varying vec2 texCoord;
varying vec3 projCoord;

// World view matrix to get object position in view space
uniform mat4 worldView;

// Attributes of light
uniform vec3 lightDiffuseColor;
uniform vec3 lightSpecularColor;
uniform vec3 lightFalloff;

void main()
{
        vec4 a0 = texture2D(tex0, texCoord); // Attribute 0: Diffuse color+shininess
    vec4 a1 = texture2D(tex1, texCoord); // Attribute 1: Normal+depth

    // Attributes
    vec3 colour = a0.rgb;
    float alpha = a0.a;         // Specularity
    float distance = a1.w;  // Distance from viewer (w)
    vec3 normal = a1.xyz;

        // Calculate position of texel in view space
    vec3 position = projCoord*distance;
        
        // Extract position in view space from worldView matrix
        //vec3 lightPos = vec3(worldView[0][3],worldView[1][3],worldView[2][3]);
        vec3 lightPos = vec3(worldView[3][0],worldView[3][1],worldView[3][2]);
        
    // Calculate light direction and distance
    vec3 lightVec = lightPos - position;
    float len_sq = dot(lightVec, lightVec);
    float len = sqrt(len_sq);
    vec3 lightDir = lightVec/len;
    
    /// Calculate attenuation    
    float attenuation = dot(lightFalloff, vec3(1, len, len_sq));
    
    /// Calculate diffuse colour
    vec3 light_diffuse = max(0.0,dot(lightDir, normal)) * lightDiffuseColor;
    
    /// Calculate specular component
    vec3 viewDir = -normalize(position);
    vec3 h = normalize(viewDir + lightDir);
    vec3 light_specular = pow(dot(normal, h),32.0) * lightSpecularColor;
    
    // Calcalate total lighting for this fragment
    vec3 total_light_contrib;
    total_light_contrib = light_diffuse;
        // Uncomment next line if specular desired
        //total_light_contrib += alpha * light_specular;
        
    gl_FragColor = vec4(total_light_contrib*colour/attenuation, 0);
    //gl_FragColor = vec4(1.0/attenuation, 0.0,0.0,0.0);
    //gl_FragColor = vec4(a1.xyz,  0.0);
}