89 lines
3.2 KiB
GLSL
89 lines
3.2 KiB
GLSL
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const int NUM_WAVES = 16;
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uniform vec3 osgOcean_Origin; // central position of vertices - sun position on water surface
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uniform vec3 osgOcean_Extinction_c; // extinction coefficient
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uniform vec3 osgOcean_Eye; // Eye position in world space
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uniform vec3 osgOcean_SunDir; // sunlight direction
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uniform float osgOcean_Spacing; // spacing between vertices
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uniform float osgOcean_Waves[NUM_WAVES * 5]; // wave constants
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varying vec3 vIntensity;
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float fastFresnel(vec3 I, vec3 N, float r0)
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{
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return r0 + (1.0-r0) * pow(1.0-dot(I, N), 5.0);
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}
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vec3 calculateWaterNormal(float x0, float y0)
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{
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vec3 t1 = vec3(1.0,0.0,0.0);
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vec3 t2 = vec3(0.0,1.0,0.0);
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int itr = NUM_WAVES/4;
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for (int i = 0, j = 0; i < itr; i++, j += 20)
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{
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vec4 kx = vec4( osgOcean_Waves[j+0], osgOcean_Waves[j+1], osgOcean_Waves[j+2], osgOcean_Waves[j+3] );
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vec4 ky = vec4( osgOcean_Waves[j+4], osgOcean_Waves[j+5], osgOcean_Waves[j+6], osgOcean_Waves[j+7] );
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vec4 Ainvk = vec4( osgOcean_Waves[j+8], osgOcean_Waves[j+9], osgOcean_Waves[j+10], osgOcean_Waves[j+11] );
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vec4 A = vec4( osgOcean_Waves[j+12], osgOcean_Waves[j+13], osgOcean_Waves[j+14], osgOcean_Waves[j+15] );
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vec4 wt = vec4( osgOcean_Waves[j+16], osgOcean_Waves[j+17], osgOcean_Waves[j+18], osgOcean_Waves[j+19] );
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vec4 phase = (kx*x0 + ky*y0 - wt);
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vec4 sinp, cosp;
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#if 1
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sinp = sin(phase);
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cosp = cos(phase);
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#else
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sincos(phase, sinp, cosp);
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#endif
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// Update tangent vector along x0
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t1.x -= dot(Ainvk, kx*cosp*kx);
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t1.y -= dot(Ainvk, ky*cosp*kx);
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t1.z += dot(A, (-sinp)*(kx));
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// Update tangent vector along y0
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t2.x -= dot(Ainvk, kx*cosp*ky);
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t2.y -= dot(Ainvk, ky*cosp*ky);
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t2.z += dot(A, (-sinp)*(ky));
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}
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// Calculate and return normal
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return normalize( cross(t1, t2) );
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}
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void main(void)
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{
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gl_TexCoord[0] = gl_MultiTexCoord0;
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// Scale and translate the vertex on the water surface
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vec3 worldPos = gl_Vertex.xyz * vec3(osgOcean_Spacing,osgOcean_Spacing,1.0);
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worldPos += osgOcean_Origin;
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// Calculate the water normal at this point
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vec3 normal = calculateWaterNormal(worldPos.x, worldPos.y);
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// Calculate transmittance
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// BUG: makes intensity too small not sure why.
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float transmittance = 1.0-fastFresnel(-osgOcean_SunDir, normal, 0.0204);
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// Extrude bottom vertices along the direction of the refracted
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// sunlight
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if (gl_TexCoord[0].s > 0.0)
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{
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// Calculate refraction vector and extrude polygon
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vec3 refr = refract(osgOcean_SunDir, normal, 0.75);
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worldPos += refr*gl_TexCoord[0].s;
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}
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// Set intensity so that the further away you go from the surface
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float totalDist = gl_TexCoord[0].s + length(worldPos-osgOcean_Eye);
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vIntensity = exp(-totalDist*osgOcean_Extinction_c)*transmittance;
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vIntensity = clamp(vIntensity, 0.0, 0.06);
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// Transform position from world to clip space
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gl_Position = gl_ModelViewProjectionMatrix * vec4(worldPos, 1.0 );
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// Tweak z position not to clip shafts very close to the viewer
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gl_Position.z = 0.01;
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}
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