pub const FXAA_FRAG: &str = "// fxaa.frag \u{2014} fast approximate anti-aliasing, run on the finished LDR frame.\r\n//\r\n// The picture is built from hundreds of thousands of small quads, and every\r\n// one of them has a hard edge. The composite\'s unsharp mask makes those edges\r\n// crisper still. FXAA finds edges by local luma contrast, walks along them to\r\n// find their ends, and blends across them by exactly the amount the edge\r\n// geometry calls for. It is the standard Lottes algorithm at the \"quality\"\r\n// preset: twelve search steps, sub-pixel blending at three quarters.\r\n//\r\n// It runs between the composite and the HUD, so the interface on top stays\r\n// exactly as sharp as it was drawn.\r\n#version 330 core\r\n\r\nin vec2 f_uv;\r\nuniform sampler2D u_image;\r\nout vec4 o_color;\r\n\r\nconst float EDGE_THRESHOLD_MIN = 0.0312;\r\nconst float EDGE_THRESHOLD_MAX = 0.125;\r\nconst int ITERATIONS = 12;\r\nconst float SUBPIXEL_QUALITY = 0.75;\r\n\r\n// Search step growth: tight for the first few, then long strides.\r\nfloat quality(int i) {\r\n if (i < 5) return 1.0;\r\n if (i == 5) return 1.5;\r\n if (i < 10) return 2.0;\r\n if (i == 10) return 4.0;\r\n return 8.0;\r\n}\r\n\r\nfloat luma(vec3 rgb) {\r\n return sqrt(dot(rgb, vec3(0.299, 0.587, 0.114)));\r\n}\r\n\r\nvoid main() {\r\n vec2 texel = 1.0 / vec2(textureSize(u_image, 0));\r\n vec3 colorCenter = texture(u_image, f_uv).rgb;\r\n float lumaCenter = luma(colorCenter);\r\n float lumaDown = luma(textureOffset(u_image, f_uv, ivec2( 0, -1)).rgb);\r\n float lumaUp = luma(textureOffset(u_image, f_uv, ivec2( 0, 1)).rgb);\r\n float lumaLeft = luma(textureOffset(u_image, f_uv, ivec2(-1, 0)).rgb);\r\n float lumaRight = luma(textureOffset(u_image, f_uv, ivec2( 1, 0)).rgb);\r\n\r\n float lumaMin = min(lumaCenter, min(min(lumaDown, lumaUp), min(lumaLeft, lumaRight)));\r\n float lumaMax = max(lumaCenter, max(max(lumaDown, lumaUp), max(lumaLeft, lumaRight)));\r\n float lumaRange = lumaMax - lumaMin;\r\n\r\n // Flat: nothing to do.\r\n if (lumaRange < max(EDGE_THRESHOLD_MIN, lumaMax * EDGE_THRESHOLD_MAX)) {\r\n o_color = vec4(colorCenter, 1.0);\r\n return;\r\n }\r\n\r\n float lumaDownLeft = luma(textureOffset(u_image, f_uv, ivec2(-1, -1)).rgb);\r\n float lumaUpRight = luma(textureOffset(u_image, f_uv, ivec2( 1, 1)).rgb);\r\n float lumaUpLeft = luma(textureOffset(u_image, f_uv, ivec2(-1, 1)).rgb);\r\n float lumaDownRight = luma(textureOffset(u_image, f_uv, ivec2( 1, -1)).rgb);\r\n\r\n float lumaDownUp = lumaDown + lumaUp;\r\n float lumaLeftRight = lumaLeft + lumaRight;\r\n float lumaLeftCorners = lumaDownLeft + lumaUpLeft;\r\n float lumaDownCorners = lumaDownLeft + lumaDownRight;\r\n float lumaRightCorners = lumaDownRight + lumaUpRight;\r\n float lumaUpCorners = lumaUpRight + lumaUpLeft;\r\n\r\n float edgeHorizontal = abs(-2.0 * lumaLeft + lumaLeftCorners)\r\n + abs(-2.0 * lumaCenter + lumaDownUp) * 2.0\r\n + abs(-2.0 * lumaRight + lumaRightCorners);\r\n float edgeVertical = abs(-2.0 * lumaUp + lumaUpCorners)\r\n + abs(-2.0 * lumaCenter + lumaLeftRight) * 2.0\r\n + abs(-2.0 * lumaDown + lumaDownCorners);\r\n bool isHorizontal = edgeHorizontal >= edgeVertical;\r\n\r\n float luma1 = isHorizontal ? lumaDown : lumaLeft;\r\n float luma2 = isHorizontal ? lumaUp : lumaRight;\r\n float gradient1 = luma1 - lumaCenter;\r\n float gradient2 = luma2 - lumaCenter;\r\n bool is1Steepest = abs(gradient1) >= abs(gradient2);\r\n float gradientScaled = 0.25 * max(abs(gradient1), abs(gradient2));\r\n\r\n float stepLength = isHorizontal ? texel.y : texel.x;\r\n float lumaLocalAverage;\r\n if (is1Steepest) {\r\n stepLength = -stepLength;\r\n lumaLocalAverage = 0.5 * (luma1 + lumaCenter);\r\n } else {\r\n lumaLocalAverage = 0.5 * (luma2 + lumaCenter);\r\n }\r\n\r\n vec2 currentUv = f_uv;\r\n if (isHorizontal) currentUv.y += stepLength * 0.5;\r\n else currentUv.x += stepLength * 0.5;\r\n\r\n vec2 offset = isHorizontal ? vec2(texel.x, 0.0) : vec2(0.0, texel.y);\r\n vec2 uv1 = currentUv - offset;\r\n vec2 uv2 = currentUv + offset;\r\n float lumaEnd1 = luma(texture(u_image, uv1).rgb) - lumaLocalAverage;\r\n float lumaEnd2 = luma(texture(u_image, uv2).rgb) - lumaLocalAverage;\r\n bool reached1 = abs(lumaEnd1) >= gradientScaled;\r\n bool reached2 = abs(lumaEnd2) >= gradientScaled;\r\n bool reachedBoth = reached1 && reached2;\r\n if (!reached1) uv1 -= offset;\r\n if (!reached2) uv2 += offset;\r\n\r\n if (!reachedBoth) {\r\n for (int i = 2; i < ITERATIONS; i++) {\r\n if (!reached1) lumaEnd1 = luma(texture(u_image, uv1).rgb) - lumaLocalAverage;\r\n if (!reached2) lumaEnd2 = luma(texture(u_image, uv2).rgb) - lumaLocalAverage;\r\n reached1 = abs(lumaEnd1) >= gradientScaled;\r\n reached2 = abs(lumaEnd2) >= gradientScaled;\r\n reachedBoth = reached1 && reached2;\r\n if (!reached1) uv1 -= offset * quality(i);\r\n if (!reached2) uv2 += offset * quality(i);\r\n if (reachedBoth) break;\r\n }\r\n }\r\n\r\n float distance1 = isHorizontal ? (f_uv.x - uv1.x) : (f_uv.y - uv1.y);\r\n float distance2 = isHorizontal ? (uv2.x - f_uv.x) : (uv2.y - f_uv.y);\r\n bool isDirection1 = distance1 < distance2;\r\n float distanceFinal = min(distance1, distance2);\r\n float edgeThickness = distance1 + distance2;\r\n float pixelOffset = -distanceFinal / edgeThickness + 0.5;\r\n\r\n bool isLumaCenterSmaller = lumaCenter < lumaLocalAverage;\r\n bool correctVariation = ((isDirection1 ? lumaEnd1 : lumaEnd2) < 0.0) != isLumaCenterSmaller;\r\n float finalOffset = correctVariation ? pixelOffset : 0.0;\r\n\r\n // Sub-pixel: blend by how far the centre is from the local average.\r\n float lumaAverage = (1.0 / 12.0) * (2.0 * (lumaDownUp + lumaLeftRight) + lumaLeftCorners + lumaRightCorners);\r\n float subPixelOffset1 = clamp(abs(lumaAverage - lumaCenter) / lumaRange, 0.0, 1.0);\r\n float subPixelOffset2 = (-2.0 * subPixelOffset1 + 3.0) * subPixelOffset1 * subPixelOffset1;\r\n float subPixelOffsetFinal = subPixelOffset2 * subPixelOffset2 * SUBPIXEL_QUALITY;\r\n finalOffset = max(finalOffset, subPixelOffsetFinal);\r\n\r\n vec2 finalUv = f_uv;\r\n if (isHorizontal) finalUv.y += finalOffset * stepLength;\r\n else finalUv.x += finalOffset * stepLength;\r\n\r\n o_color = vec4(texture(u_image, finalUv).rgb, 1.0);\r\n}\r\n";Expand description
Anti-aliasing on the finished LDR frame, before the HUD.