FXAA + Fiddling

Signed-off-by: Robear Selwans <robear.selwans@outlook.com>

assets/shaders/fxaa.frag

@@ -1,13 +1,69 @@
 #version 450
 
-layout(set = 0, binding = 0) uniform sampler2D ppIN;
+layout(set = 0, binding = 0) uniform sampler2D ppIn;
 
-layout (location = 0) in vec2 outUV;
+// layout (location = 0) in vec2 uv;
 
 layout(location = 0) out vec4 outColor;
 
+const vec2 resolution = vec2(1920, 1080);
+
+#define FXAA_SUBPIX_SHIFT (1.0/4.0)
+#define FXAA_SPAN_MAX 32.0
+#define FXAA_REDUCE_MUL   (1.0/FXAA_SPAN_MAX)
+#define FXAA_REDUCE_MIN   (1.0/256.0)
+
 void main()
 {
-  vec3 color = texture(ppIN, outUV).rgb;
-  outColor = vec4(color, 1.0);
+  vec2 rcpFrame = 1./resolution.xy;
+  vec2 uv2 = gl_FragCoord.xy / resolution.xy;
+
+  vec4 uv = vec4(uv2, uv2 - (rcpFrame * (0.5 + FXAA_SUBPIX_SHIFT)));
+
+  vec3 luma = vec3(0.299, 0.587, 0.114);
+
+  vec3 rgbNW = texture(ppIn, uv.zw).xyz;
+  vec3 rgbNE = texture(ppIn, uv.zw + vec2(1,0)*rcpFrame.xy).xyz;
+  vec3 rgbSW = texture(ppIn, uv.zw + vec2(0,1)*rcpFrame.xy).xyz;
+  vec3 rgbSE = texture(ppIn, uv.zw + vec2(1,1)*rcpFrame.xy).xyz;
+  vec3 rgbM  = texture(ppIn, uv.xy).xyz;
+
+  float lumaNW = dot(rgbNW, luma);
+  float lumaNE = dot(rgbNE, luma);
+  float lumaSW = dot(rgbSW, luma);
+  float lumaSE = dot(rgbSE, luma);
+  float lumaM  = dot(rgbM,  luma);
+
+  float lumaMin = min(lumaM, min(min(lumaNW, lumaNE), min(lumaSW, lumaSE)));
+  float lumaMax = max(lumaM, max(max(lumaNW, lumaNE), max(lumaSW, lumaSE)));
+
+  vec2 dir;
+  dir.x = -((lumaNW + lumaNE) - (lumaSW + lumaSE));
+  dir.y =  ((lumaNW + lumaSW) - (lumaNE + lumaSE));
+
+  float dirReduce = max(
+    (lumaNW + lumaNE + lumaSW + lumaSE) * (0.25 * FXAA_REDUCE_MUL),
+    FXAA_REDUCE_MIN);
+  float rcpDirMin = 1.0/(min(abs(dir.x), abs(dir.y)) + dirReduce);
+  
+  dir = min(vec2( FXAA_SPAN_MAX,  FXAA_SPAN_MAX),
+        max(vec2(-FXAA_SPAN_MAX, -FXAA_SPAN_MAX),
+        dir * rcpDirMin)) * rcpFrame.xy;
+
+  vec3 rgbA = (1.0/2.0) * (
+      texture(ppIn, uv.xy + dir * (1.0/3.0 - 0.5)).xyz +
+      texture(ppIn, uv.xy + dir * (2.0/3.0 - 0.5)).xyz);
+  vec3 rgbB = rgbA * (1.0/2.0) + (1.0/4.0) * (
+      texture(ppIn, uv.xy + dir * (0.0/3.0 - 0.5)).xyz +
+      texture(ppIn, uv.xy + dir * (3.0/3.0 - 0.5)).xyz);
+  
+  float lumaB = dot(rgbB, luma);
+
+  if((lumaB < lumaMin) || (lumaB > lumaMax)) 
+    outColor = vec4(rgbA, 1.0);
+  else
+    outColor = vec4(rgbB, 1.0);
+
+  if(uv.x < 0.5)
+    outColor = vec4(rgbM, 1.0);
 }