source: data/branches/Shader_HS18/programs/Example/GLSL/SwizzleGP.glsl @ 12083

#version 120                                                                                                                                                            
#extension GL_EXT_geometry_shader4 : enable                                                                                                     

uniform vec4 origColor;                                                                                                                                         
uniform vec4 cloneColor;                                                                                                                                        

void main(void)                                                                                                                                                         
{                                                                                                                                                                                       

        //increment variable                                                                                                                                    
        int i;                                                                                                                                                                  

        /////////////////////////////////////////////////////////////                                                   
        //This example has two parts                                                                                                                    
        //      step a) draw the primitive pushed down the pipeline                                                                     
        //               there are gl_Vertices # of vertices                                                                                    
        //               put the vertex value into gl_Position                                                                                  
        //               use EmitVertex => 'create' a new vertex                                                                                
        //              use EndPrimitive to signal that you are done creating a primitive!                              
        //      step b) create a new piece of geometry (I.E. WHY WE ARE USING A GEOMETRY SHADER!)       
        //              I just do the same loop, but swizzle the x and y values                                                 
        //      result => the line we want to draw, and the same line, but along the other axis         

        //Pass-thru!                                                                                                                                                    
        for(i=0; i< gl_VerticesIn; i++){                                                                                                                
                gl_Position = gl_PositionIn[i];                                                                                                         
                gl_FrontColor = origColor;                                                                                                                      
                EmitVertex();                                                                                                                                           
        }                                                                                                                                                                               
        EndPrimitive();                                                                                                                                                 
        //New piece of geometry!  We just swizzle the x and y terms                                                             
        for(i=0; i< gl_VerticesIn; i++){                                                                                                                
                gl_Position = gl_PositionIn[i];                                                                                                         
                gl_Position.xy = gl_Position.yx;                                                                                                        
                gl_FrontColor = cloneColor;                                                                                                                     
                EmitVertex();                                                                                                                                           
        }                                                                                                                                                                               
        EndPrimitive();                                                                                                                                                 

}