55 lines
1.3 KiB
GLSL
55 lines
1.3 KiB
GLSL
#version 430 core
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layout (points) in;
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layout (triangle_strip, max_vertices = 11) out;
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uniform vec2 lightPos;
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uniform mat4 worldMat;
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vec2 lightPosa = ( worldMat * vec4(lightPos,0,1) ).xy;
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vec4 shift (vec4 p)
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{ return vec4 (p.xy + (200 * (p.xy-lightPos)), 0 , 1);
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}
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float isLHS (vec2 startV, vec2 testV)
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{
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return sign( -startV.x * testV.y + startV.y * testV.x);
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}
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// construct a box with openings on bottom face and face away from wall
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void main()
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{
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vec4 p1 = vec4 (gl_in[0].gl_Position.xy,0,1);
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vec4 p2 = vec4 (gl_in[0].gl_Position.zw,0,1);
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if (isLHS (p1.xy - lightPos, p2.xy - lightPos) < 0)
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{
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vec4 p3 = vec4 (p1.xy,-0.5,1);
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vec4 p4 = vec4 (p2.xy,-0.5,1);
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vec4 p5 = shift(p1);
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vec4 p6 = shift(p2);
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vec4 p7 = vec4 (p6.xy,-0.5,1);
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vec4 p8 = vec4 (p5.xy,-0.5,1);
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vec4 a1 = worldMat * p1;
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vec4 a2 = worldMat * p2;
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vec4 a3 = worldMat * p3;
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vec4 a4 = worldMat * p4;
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vec4 a5 = worldMat * p5;
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vec4 a6 = worldMat * p6;
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vec4 a7 = worldMat * p7;
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vec4 a8 = worldMat * p8;
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gl_Position = a4; EmitVertex();
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gl_Position = a3; EmitVertex();
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gl_Position = a7; EmitVertex();
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gl_Position = a8; EmitVertex();
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gl_Position = a5; EmitVertex();
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gl_Position = a3; EmitVertex();
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gl_Position = a1; EmitVertex();
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gl_Position = a4; EmitVertex();
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gl_Position = a2; EmitVertex();
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gl_Position = a7; EmitVertex();
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gl_Position = a6; EmitVertex();
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EndPrimitive();
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} else {}
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}
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