gl/gen_line_strip/geom.glsl

0001 #version 410 core
0002
0003 // https://www.opengl.org/wiki/Geometry_Shader
0004
0005 uniform mat4 ModelViewProjection ;
0006 uniform vec4 Param ;
0007 in vec4 deltapos[];
0008
0009 layout (points) in;
0010 layout (line_strip, max_vertices = 2) out;
0011
0012 out vec4 fcolor ;
0013
0014
0015 void main ()
0016 {
0017     vec4 p0 = gl_in[0].gl_Position ;
0018     vec4 p1 = gl_in[0].gl_Position + deltapos[0]  ;
0019     // p1.w is gibberish : adding time to step_length
0020
0021     float t0 = p0.w ;
0022     float tc = Param.w  ;
0023
0024     fcolor = vec4(1.0,1.0,1.0,1.0) ;
0025
0026     if( tc > t0 )
0027     {
0028         gl_Position = ModelViewProjection * vec4( vec3(p0), 1.0 ) ;
0029         EmitVertex();
0030
0031         gl_Position = ModelViewProjection * vec4( vec3(p1), 1.0 ) ;
0032         EmitVertex();
0033     }
0034
0035     EndPrimitive();
0036 }