67 lines
1.8 KiB
GLSL
67 lines
1.8 KiB
GLSL
#version 110
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#extension GL_EXT_gpu_shader4 : enable
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uniform bool perspective;
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uniform vec2 p0;
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uniform vec2 p1;
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uniform vec2 p2;
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uniform vec2 p3;
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varying vec2 q;
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varying vec2 b1;
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varying vec2 b2;
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varying vec2 b3;
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varying vec2 vTexCoord;
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void main() {
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gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
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if (perspective) {
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float m1 = (p3.y - p0.y)/(p3.x - p0.x);
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float c1 = p0.y - m1 * p0.x;
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float m2 = (p1.y - p2.y)/(p1.x - p2.x);
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float c2 = p2.y - m2 * p2.x;
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float mid_x = (c2 - c1) / (m1 - m2);
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float mid_y = m1 * mid_x + c1;
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float d0 = sqrt(pow(mid_x - p0.x, 2.0) + pow(mid_y - p0.y, 2.0));
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float d1 = sqrt(pow(p1.x - mid_x, 2.0) + pow(mid_y - p1.y, 2.0));
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float d2 = sqrt(pow(p3.x - mid_x, 2.0) + pow(p3.y - mid_y, 2.0));
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float d3 = sqrt(pow(mid_x - p2.x, 2.0) + pow(p2.y - mid_y, 2.0));
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float q;
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if (gl_VertexID == 0) {
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q = (d1+d3)/d3;
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} else if (gl_VertexID == 1) {
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q = (d0+d2)/d2;
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} else if (gl_VertexID == 2) {
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q = (d3+d1)/d1;
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} else {
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q = (d2+d0)/d0;
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}
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gl_Position[0] *= q;
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gl_Position[1] *= q;
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gl_Position[3] = q;
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vTexCoord = gl_MultiTexCoord0.xy;
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} else {
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vec2 pos;
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if (gl_VertexID == 0) { // top left
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pos = p2;
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} else if (gl_VertexID == 1) { // top right
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pos = p3;
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} else if (gl_VertexID == 2) { // bottom right
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pos = p1;
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} else if (gl_VertexID == 3) { // bottom left
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pos = p0;
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}
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q = pos - p0;
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b1 = p1 - p0;
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b2 = p2 - p0;
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b3 = p0 - p1 - p2 + p3;
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}
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} |