CrossStitch.glsl

#include "Uniforms.glsl"
#include "Samplers.glsl"
#include "Transform.glsl"
#include "ScreenPos.glsl"

varying vec2 vScreenPos;

uniform float rt_w;
uniform float rt_h;
uniform float stitching_size = 8.0;
uniform int invert = 1;

void VS()
{
    mat4 modelMatrix = iModelMatrix;
    vec3 worldPos = GetWorldPos(modelMatrix);
    gl_Position = GetClipPos(worldPos);
    vScreenPos = GetScreenPosPreDiv(gl_Position);
}

vec4 PostFX(sampler2D tex, vec2 uv)
{
  
  float rt_w = 1024.0;
  float rt_h = 768.0;

  vec4 c = vec4(0.0);
  float size = stitching_size;
  vec2 cPos = uv * vec2(rt_w, rt_h);
  
  vec2 tlPos = floor(cPos / vec2(size, size));
  tlPos *= size;
  int remX = int(mod(cPos.x, size));
  int remY = int(mod(cPos.y, size));
  if (remX == 0 && remY == 0)
    tlPos = cPos;
  vec2 blPos = tlPos;
  blPos.y += (size - 1.0);
  if ((remX == remY) || 
     (((int(cPos.x) - int(blPos.x)) == (int(blPos.y) - int(cPos.y)))))
  {
    if (invert == 1)
      c = vec4(0.2, 0.15, 0.05, 1.0);
    else
      c = texture2D(tex, tlPos * vec2(1.0/rt_w, 1.0/rt_h)) * 1.4;
  }
  else
  {
    if (invert == 1)
      c = texture2D(tex, tlPos * vec2(1.0/rt_w, 1.0/rt_h)) * 1.4;
    else
      c = vec4(0.0, 0.0, 0.0, 1.0);
  }
  return c;
}
 
void PS()
{
  vec2 uv = vScreenPos.xy;
  gl_FragColor = PostFX(sDiffMap, uv);
}