source: downloads/Samples/Media/DeferredShadingMedia/DeferredShading/post/glsl/Ambient_ps.glsl @ 1

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

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/** Deferred shading framework
        // W.J. :wumpus: van der Laan 2005 //
        
        Post shader: Multipass, ambient (base) pass
*/
uniform sampler2D tex0;
uniform sampler2D tex1;

varying vec2 texCoord;
varying vec3 projCoord;

uniform mat4 proj;

uniform vec3 ambientColor;

void main()
{
        vec4 a0 = texture2D(tex0, texCoord); // Attribute 0: Diffuse color+shininess
    vec4 a1 = texture2D(tex1, texCoord); // Attribute 1: Normal+depth
    
    // Clip fragment if depth is too far, so the skybox can be rendered on the background
    if(a1.w==0.0)
                discard;
      
    // Attributes
    vec3 colour = a0.rgb;
    float alpha = a0.a;         // Specularity
    float distance = a1.w;  // Distance from viewer -- is zero if no lighting wanted
    
        // Calculate ambient colour of fragment
    gl_FragColor = vec4( ambientColor*colour ,0);
    
    // Calculate depth of fragment; GL requires a 2.0* here as the range is [-1, 1]
    // Also, see again how matrix is transposed ([3][2] instead of [2][3])
    gl_FragDepth = projCoord.z*proj[2][2] + proj[3][2]/(2.0*distance);
}