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Project wall shadows onto other walls

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jgk
2021-03-19 12:40:07 +01:00
parent e079289349
commit 5a7be55e24
5 changed files with 102 additions and 71 deletions
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shader/wallShadow.geom
+64 -9
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@@ -1,26 +1,81 @@
#version 430 core
layout (points) in;
layout (triangle_strip, max_vertices = 4) out;
layout (triangle_strip, max_vertices = 12) out;
uniform vec2 lightPos;
uniform mat4 worldMat;
vec4 shift (vec4 p)
{ return vec4 (p.xy + (200 * (p.xy-lightPos)), 0 , 1);
}
float isLHS (vec2 startV, vec2 testV)
{
return sign( -startV.x * testV.y + startV.y * testV.x);
}
void emitLine (vec2 pa)
{
gl_Position = vec4 (pa, 0, 1);
EmitVertex();
gl_Position = vec4 (pa + (200 * (pa - lightPos)), 0 , 1);
gl_Position = shift (vec4 (pa,0,1)); //vec4 (pa + (200 * (pa - lightPos)), 0 , 1);
EmitVertex();
}
mat4 perspective =
mat4 (1,0,0,0
,0,1,0,0
,0,0,1,1
,0,0,0,1
) ;
// construct a box with opening on bottom face
void main()
{
vec4 frontL4 = worldMat * vec4(gl_in[0].gl_Position.xy, 0 ,1);
vec4 frontR4 = worldMat * vec4(gl_in[0].gl_Position.zw, 0 ,1);
vec2 frontL = frontL4.xy;
vec2 frontR = frontR4.xy;
emitLine (frontR);
emitLine (frontL);
vec4 p1 = worldMat * vec4 (gl_in[0].gl_Position.xy,0,1);
vec4 p2 = worldMat * vec4 (gl_in[0].gl_Position.zw,0,1);
if (isLHS (p1.xy - lightPos, p2.xy - lightPos) < 0)
{
vec4 p3 = vec4 (p1.xy,-0.5,1);
vec4 p4 = vec4 (p2.xy,-0.5,1);
vec4 p5 = shift(p1);
vec4 p6 = shift(p2);
vec4 p7 = vec4 (p6.xy,-0.5,1);
vec4 p8 = vec4 (p5.xy,-0.5,1);
gl_Position = perspective * p4; EmitVertex();
gl_Position = perspective * p3; EmitVertex();
gl_Position = perspective * p7; EmitVertex();
gl_Position = perspective * p8; EmitVertex();
gl_Position = perspective * p5; EmitVertex();
gl_Position = perspective * p3; EmitVertex();
gl_Position = perspective * p1; EmitVertex();
gl_Position = perspective * p4; EmitVertex();
gl_Position = perspective * p2; EmitVertex();
gl_Position = perspective * p7; EmitVertex();
gl_Position = perspective * p6; EmitVertex();
gl_Position = perspective * p5; EmitVertex();
EndPrimitive();
} else {}
}
// // void main()
// // {
// // vec4 frontL4 = worldMat * vec4(gl_in[0].gl_Position.xy, 0 ,1);
// // vec4 frontR4 = worldMat * vec4(gl_in[0].gl_Position.zw, 0 ,1);
// // vec2 frontL = frontL4.xy;
// // vec2 frontR = frontR4.xy;
// //
// // emitLine (frontR);
// // emitLine (frontL);
// // EndPrimitive();
// // }
// gl_Position = perspective * worldMat * p4; EmitVertex();
// gl_Position = perspective * worldMat * p3; EmitVertex();
// gl_Position = perspective * worldMat * p7; EmitVertex();
// gl_Position = perspective * worldMat * p8; EmitVertex();
// gl_Position = perspective * worldMat * p5; EmitVertex();
// gl_Position = perspective * worldMat * p3; EmitVertex();
// gl_Position = perspective * worldMat * p1; EmitVertex();
// gl_Position = perspective * worldMat * p4; EmitVertex();
// gl_Position = perspective * worldMat * p2; EmitVertex();
// gl_Position = perspective * worldMat * p7; EmitVertex();
// gl_Position = perspective * worldMat * p6; EmitVertex();
// gl_Position = perspective * worldMat * p5; EmitVertex();