59 lines
1.8 KiB
GLSL
59 lines
1.8 KiB
GLSL
#version 430 core
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layout (lines_adjacency) in;
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layout (triangle_strip, max_vertices = 4) out;
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layout (std140, binding = 0) uniform TheMat { mat4 theMat; } ;
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uniform vec3 lightPos;
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vec4 shift (vec4 p) { return (vec4 (p.xyz + (100000*(p.xyz-lightPos)), 1));}
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// copied from lighting/cap.geom
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vec4 projNear (vec4 pos)
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{
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// note we project to a specific height
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// this is quite brittle, not ideal
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vec3 dir = pos.xyz - lightPos ;
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float a = (140 - pos.z) / dir.z ;
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vec2 xy = (pos.xyz + a * dir).xy ;
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return vec4 ( xy, 140 , 1) ;
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}
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vec4 shiftNear (vec4 pos)
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{ vec4 sp = shift(pos);
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if (sp.z > 140)
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{ return projNear(pos) ; }
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else
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{ return sp ; }
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}
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vec4 f (vec4 p) {return (theMat * p);}
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void main()
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{
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vec4 p0 = gl_in[0].gl_Position;
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vec3 n0 = gl_in[2].gl_Position.xyz;
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vec3 n1 = gl_in[3].gl_Position.xyz;
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//vec3 n2 = n0 + n1; // assumes the summands are normalized
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vec3 lightDir = p0.xyz - lightPos.xyz;
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// first test if the edge is part of the silhouette
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// that is, if the normals of the faces connected by the edge point in
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// "different directions" wrt the light direction
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if ( dot(n0 , lightDir) * dot(n1 , lightDir) < 0 )
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{
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vec4 p1 = gl_in[1].gl_Position;
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vec4 p2 = shiftNear(p0);
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vec4 p3 = shiftNear(p1);
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if ( dot(n0 , lightDir) > 0)
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{
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gl_Position = f(p0); EmitVertex();
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gl_Position = f(p1); EmitVertex();
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gl_Position = f(p2); EmitVertex();
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gl_Position = f(p3); EmitVertex();
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}
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else
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{
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gl_Position = f(p1); EmitVertex();
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gl_Position = f(p0); EmitVertex();
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gl_Position = f(p3); EmitVertex();
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gl_Position = f(p2); EmitVertex();
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}
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EndPrimitive();
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}
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else { }
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}
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