#ifdef GL_ES
precision mediump int;
precision mediump float;
#endif

#define USE_OGRE_FROM_FUTURE
#include <OgreUnifiedShader.h>

SAMPLER2D(RT, 0);

OGRE_UNIFORMS(
uniform float NumTiles;
uniform float Threshold;
)

MAIN_PARAMETERS
IN(vec2 oUv0, TEXCOORD0)
MAIN_DECLARATION
{
  vec3 EdgeColor = vec3(0.7, 0.7, 0.7);

  float size = 1.0 / NumTiles;
  vec2 Pbase = oUv0 - mod(oUv0, vec2_splat(size));
  vec2 PCenter = Pbase + vec2_splat(size/2.0);
  vec2 st = (oUv0 - Pbase) / vec2_splat(size);
  vec4 c1 = vec4_splat(0.0);
  vec4 c2 = vec4_splat(0.0);
  vec4 invOff = vec4((1.0-EdgeColor), 1.0);
  if (st.x > st.y) { c1 = invOff; }
  
  float threshholdB = 1.0 - Threshold;
  
  if (st.x > threshholdB) { c2 = c1; }
  if (st.y > threshholdB) { c2 = c1; }
  
  vec4 cBottom = c2;
  c1 = vec4_splat(0.0);
  c2 = vec4_splat(0.0);
  
  if (st.x > st.y) { c1 = invOff; }
  if (st.x < Threshold) { c2 = c1; }
  if (st.y < Threshold) { c2 = c1; }
  vec4 cTop = c2;
  vec4 tileColor = texture2D(RT, PCenter);
  vec4 result = tileColor + cTop - cBottom;
  gl_FragColor = result;
}