uniform mat4 modelMatrix;
 uniform mat4 projMatrix;
 uniform sampler2D tex;
 uniform ivec2 res;
 out vec4 oColor;
 struct Tri{
 vec4 v0;
 vec4 v1;
 vec4 v2;
 vec2 uv0;
 vec2 uv1;
 vec2 uv2;
 };


  vec4 vertices[4];

  void main(){
    vec2 uv = gl_FragCoord.xy / vec2(res);
    uv -= vec2(0.5);
   //build default vertices:
   vertices[0] = vec4(-1.0,-1.0,   0.0,1.0);
   vertices[1] = vec4( 1.0,-1.0,   0.0,1.0);
   vertices[2] = vec4( 1.0,1.0,    0.0,1.0);
   vertices[3] = vec4(-1.0,1.0,    0.0,1.0);

   //transform vertices:
   for(int c = 0; c < 4; ++c){
      vertices[c] = projMatrix  * modelMatrix * vertices[c];
      vertices[c].xyz   /=  vertices[c].w; //to NDC
   }
     //define triangle geometry:
   Tri tri1 = Tri(vertices[0],vertices[1],vertices[2]
       ,vec2(0.0,0.0),vec2(1.0,0.0),vec2(1.0,1.0));

    bool rasterize = false;
     vec4 colorRes = vec4(0.0);
    rasterize = drawTriangleBary(tri1, uv, colorRes);
    if(rasterize){
          oColor = colorRes;
    }else{discard;}
   }
}

for(int c = 0; c < 4; ++c){
  vertices[c] = projMatrix  * modelMatrix * vertices[c];
  vertices[c].xyz   /=  vertices[c].w * 2.0; //to NDC