Files
OpenSpace/modules/base/shaders/polygon_gs.glsl
2024-02-06 15:53:24 +01:00

57 lines
2.7 KiB
GLSL

/*****************************************************************************************
* *
* OpenSpace *
* *
* Copyright (c) 2014-2024 *
* *
* Permission is hereby granted, free of charge, to any person obtaining a copy of this *
* software and associated documentation files (the "Software"), to deal in the Software *
* without restriction, including without limitation the rights to use, copy, modify, *
* merge, publish, distribute, sublicense, and/or sell copies of the Software, and to *
* permit persons to whom the Software is furnished to do so, subject to the following *
* conditions: *
* *
* The above copyright notice and this permission notice shall be included in all copies *
* or substantial portions of the Software. *
* *
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, *
* INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A *
* PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT *
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF *
* CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE *
* OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. *
****************************************************************************************/
#version __CONTEXT__
layout(points) in;
layout(triangle_strip, max_vertices = 63) out;
uniform int sides;
const float PI = 3.1415926;
void main() {
vec4 v0 = gl_in[0].gl_Position;
for (int i = sides; i > 0; --i) {
// Angle between each side in radians
float ang = 2.0 * PI / float(sides) * i;
gl_Position = v0;
EmitVertex();
vec4 vi = v0 + vec4(cos(ang) * 0.8, -sin(ang) * 0.8, 0.0, 0.0);
gl_Position = vi;
EmitVertex();
ang = 2.0 * PI / float(sides) * (i - 1);
vec4 vii = v0 + vec4(cos(ang) * 0.8, -sin(ang) * 0.8, 0.0, 0.0);
gl_Position = vii;
EmitVertex();
EndPrimitive();
}
}