82 lines
2.6 KiB
GLSL
82 lines
2.6 KiB
GLSL
#version 430 core
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layout (points) in;
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layout (triangle_strip, max_vertices = 12) out;
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uniform vec2 lightPos;
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uniform mat4 worldMat;
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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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void emitLine (vec2 pa)
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{
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gl_Position = vec4 (pa, 0, 1);
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EmitVertex();
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gl_Position = shift (vec4 (pa,0,1)); //vec4 (pa + (200 * (pa - lightPos)), 0 , 1);
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EmitVertex();
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}
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mat4 perspective =
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mat4 (1,0,0,0
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,0,1,0,0
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,0,0,1,1
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,0,0,0,1
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) ;
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// construct a box with opening on bottom face
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void main()
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{
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vec4 p1 = worldMat * vec4 (gl_in[0].gl_Position.xy,0,1);
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vec4 p2 = worldMat * 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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gl_Position = perspective * p4; EmitVertex();
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gl_Position = perspective * p3; EmitVertex();
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gl_Position = perspective * p7; EmitVertex();
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gl_Position = perspective * p8; EmitVertex();
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gl_Position = perspective * p5; EmitVertex();
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gl_Position = perspective * p3; EmitVertex();
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gl_Position = perspective * p1; EmitVertex();
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gl_Position = perspective * p4; EmitVertex();
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gl_Position = perspective * p2; EmitVertex();
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gl_Position = perspective * p7; EmitVertex();
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gl_Position = perspective * p6; EmitVertex();
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gl_Position = perspective * p5; EmitVertex();
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EndPrimitive();
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} else {}
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}
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// // void main()
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// // {
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// // vec4 frontL4 = worldMat * vec4(gl_in[0].gl_Position.xy, 0 ,1);
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// // vec4 frontR4 = worldMat * vec4(gl_in[0].gl_Position.zw, 0 ,1);
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// // vec2 frontL = frontL4.xy;
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// // vec2 frontR = frontR4.xy;
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// //
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// // emitLine (frontR);
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// // emitLine (frontL);
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// // EndPrimitive();
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// // }
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// gl_Position = perspective * worldMat * p4; EmitVertex();
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// gl_Position = perspective * worldMat * p3; EmitVertex();
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// gl_Position = perspective * worldMat * p7; EmitVertex();
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// gl_Position = perspective * worldMat * p8; EmitVertex();
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// gl_Position = perspective * worldMat * p5; EmitVertex();
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// gl_Position = perspective * worldMat * p3; EmitVertex();
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// gl_Position = perspective * worldMat * p1; EmitVertex();
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// gl_Position = perspective * worldMat * p4; EmitVertex();
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// gl_Position = perspective * worldMat * p2; EmitVertex();
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// gl_Position = perspective * worldMat * p7; EmitVertex();
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// gl_Position = perspective * worldMat * p6; EmitVertex();
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// gl_Position = perspective * worldMat * p5; EmitVertex();
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