59 lines
1.7 KiB
GLSL
59 lines
1.7 KiB
GLSL
//this shader is a light shader. ideally drawn with a quad covering the entire region
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//the output is contribution from this light (which will be additively blended)
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//you can blame Electro for much of the maths in here.
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//fixme: no fog
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varying vec4 tf;
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#ifdef VERTEX_SHADER
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void main()
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{
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tf = ftetransform();
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gl_Position = tf;
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}
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#endif
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#ifdef FRAGMENT_SHADER
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uniform sampler2D s_t0;
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uniform vec3 l_lightposition;
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uniform mat4 m_invviewprojection;
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uniform vec3 l_lightcolour;
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uniform float l_lightradius;
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vec3 calcLightWorldPos(vec2 screenPos, float depth)
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{
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vec4 pos;
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pos.x = screenPos.x;
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pos.y = screenPos.y;
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pos.z = depth;
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pos.w = 1.0;
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pos = m_invviewprojection * pos;
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return pos.xyz / pos.w;
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}
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void main ()
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{
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vec3 lightColour = l_lightcolour.rgb;
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float lightIntensity = 1.0;
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float lightAttenuation = l_lightradius; // fixme: just use the light radius for now, use better near/far att math separately once working
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float radiusFar = l_lightradius;
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float radiusNear = l_lightradius*0.5;
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vec2 fc;
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fc = tf.xy / tf.w;
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vec4 data = texture2D(s_t0, (1.0 + fc) / 2.0);
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float depth = data.a;
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vec3 norm = data.xyz;
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/* calc where the wall that generated this sample came from */
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vec3 worldPos = calcLightWorldPos(fc, depth);
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/*calc diffuse lighting term*/
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vec3 lightDir = l_lightposition - worldPos;
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float zdiff = 1.0 - clamp(length(lightDir) / lightAttenuation, 0.0, 1.0);
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float atten = (radiusFar * zdiff) / (radiusFar - radiusNear);
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atten = pow(atten, 2.0);
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lightDir = normalize(lightDir);
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float nDotL = dot(norm, lightDir) * atten;
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float lightDiffuse = max(0.0, nDotL);
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gl_FragColor = vec4(lightDiffuse * (lightColour * lightIntensity), 1.0);
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}
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#endif
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