63 lines
1.8 KiB
Python
63 lines
1.8 KiB
Python
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$input v_normal, v_texcoord0, v_texcoord1
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#include "../common/common.sh"
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#include "parameters.sh"
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#include "normal_encoding.sh"
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SAMPLER2D(s_albedo, 0);
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SAMPLER2D(s_normal, 1);
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// http://www.thetenthplanet.de/archives/1180
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// "followup: normal mapping without precomputed tangents"
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mat3 cotangentFrame(vec3 N, vec3 p, vec2 uv)
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{
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// get edge vectors of the pixel triangle
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vec3 dp1 = dFdx(p);
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vec3 dp2 = dFdy(p);
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vec2 duv1 = dFdx(uv);
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vec2 duv2 = dFdy(uv);
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// solve the linear system
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vec3 dp2perp = cross(dp2, N);
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vec3 dp1perp = cross(N, dp1);
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vec3 T = dp2perp * duv1.x + dp1perp * duv2.x;
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vec3 B = dp2perp * duv1.y + dp1perp * duv2.y;
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// construct a scale-invariant frame
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float invMax = inversesqrt(max(dot(T,T), dot(B,B)));
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return mat3(T*invMax, B*invMax, N);
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}
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void main()
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{
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vec3 albedo = toLinear(texture2D(s_albedo, v_texcoord0).xyz);
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// get vertex normal
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vec3 normal = normalize(v_normal);
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// get normal map normal, unpack, and calculate z
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vec3 normalMap;
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normalMap.xy = texture2D(s_normal, v_texcoord0).xy;
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normalMap.xy = normalMap.xy * 2.0 - 1.0;
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normalMap.z = sqrt(1.0 - dot(normalMap.xy, normalMap.xy));
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// swap x and y, because the brick texture looks flipped, don't copy this...
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normalMap.xy = normalMap.yx;
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// perturb geometry normal by normal map
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vec3 pos = v_texcoord1.xyz; // contains world space pos
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mat3 TBN = cotangentFrame(normal, pos, v_texcoord0);
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vec3 bumpedNormal = normalize(instMul(TBN, normalMap));
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// need some proxy for roughness value w/o roughness texture
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// assume horizontal (blue) normal map is smooth, and then
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// modulate with albedo for some higher frequency detail
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float roughness = normalMap.z * mix(0.9, 1.0, albedo.y);
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roughness = roughness * 0.6 + 0.2;
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vec3 bufferNormal = NormalEncode(bumpedNormal);
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gl_FragData[0] = vec4(toGamma(albedo), 1.0);
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gl_FragData[1] = vec4(bufferNormal, roughness);
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}
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