80 lines
2.6 KiB
GLSL
80 lines
2.6 KiB
GLSL
#version 330 core
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layout(location = 0) in vec4 pos;
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layout(location = 3) in vec4 multiTexCoord0;
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out VS_OUT {
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vec2 water_texcoord;
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vec2 topo_texcoord;
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vec3 vertex_normal;
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vec3 view_vector;
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} vs_out;
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uniform mat4 osg_ModelViewMatrix;
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uniform mat4 osg_ModelViewMatrixInverse;
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uniform mat4 osg_ModelViewProjectionMatrix;
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uniform mat4 osg_ViewMatrixInverse;
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uniform mat3 osg_NormalMatrix;
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// constants for the cartesian to geodetic conversion.
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const float a = 6378137.0; //float a = equRad;
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const float squash = 0.9966471893352525192801545;
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const float latAdjust = 0.9999074159800018; //geotiff source for the depth map
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const float lonAdjust = 0.9999537058469516; //actual extents: +-180.008333333333326/+-90.008333333333340
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void get_rotation_matrix(float angle, out mat4 rotmat)
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{
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rotmat = mat4(cos(angle), -sin(angle), 0.0, 0.0,
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sin(angle), cos(angle), 0.0, 0.0,
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0.0 , 0.0 , 1.0, 0.0,
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0.0 , 0.0 , 0.0, 1.0);
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}
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vec2 get_topo_coords(vec3 rawPos)
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{
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float e2 = abs(1.0 - squash * squash);
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float ra2 = 1.0/(a * a);
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float e4 = e2 * e2;
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float XXpYY = rawPos.x * rawPos.x + rawPos.y * rawPos.y;
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float Z = rawPos.z;
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float sqrtXXpYY = sqrt(XXpYY);
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float p = XXpYY * ra2;
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float q = Z*Z*(1.0-e2)*ra2;
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float r = 1.0/6.0*(p + q - e4);
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float s = e4 * p * q/(4.0*r*r*r);
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if ( s >= 2.0 && s <= 0.0)
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s = 0.0;
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float t = pow(1.0+s+sqrt(s*2.0+s*s), 1.0/3.0);
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float u = r + r*t + r/t;
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float v = sqrt(u*u + e4*q);
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float w = (e2*u+ e2*v-e2*q)/(2.0*v);
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float k = sqrt(u+v+w*w)-w;
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float D = k*sqrtXXpYY/(k+e2);
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vec2 NormPosXY = normalize(rawPos.xy);
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vec2 NormPosXZ = normalize(vec2(D, rawPos.z));
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float signS = sign(rawPos.y);
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if (-0.00015 <= rawPos.y && rawPos.y<=.00015)
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signS = 1.0;
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float signT = sign(rawPos.z);
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if (-0.0002 <= rawPos.z && rawPos.z<=.0002)
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signT = 1.0;
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float cosLon = dot(NormPosXY, vec2(1.0,0.0));
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float cosLat = dot(abs(NormPosXZ), vec2(1.0,0.0));
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vec2 coord;
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coord.s = signS * lonAdjust * degrees(acos(cosLon))/180.;
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coord.t = signT * latAdjust * degrees(acos(cosLat))/90.;
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return coord * 0.5 + 0.5;
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}
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void main()
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{
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gl_Position = osg_ModelViewProjectionMatrix * pos;
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vs_out.water_texcoord = multiTexCoord0.st;
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vs_out.vertex_normal = osg_NormalMatrix * vec3(0.0, 0.0, 1.0);
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vs_out.view_vector = (osg_ModelViewMatrix * pos).xyz;
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vec3 raw_pos = (osg_ViewMatrixInverse * vec4(vs_out.view_vector, 1.0)).xyz;
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// Geodesy lookup for depth map
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vs_out.topo_texcoord = get_topo_coords(raw_pos);
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}
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