From 16ae2cc1bf7e29acff36eb00e8503f81a896f897 Mon Sep 17 00:00:00 2001
From: Juan Linietsky <reduzio@gmail.com>
Date: Sun, 12 Apr 2020 01:49:10 -0300
Subject: Add screen space AA option, with FXAA implementation.

---
 .../rendering/rasterizer_rd/shaders/tonemap.glsl   | 58 +++++++++++++++++++++-
 1 file changed, 56 insertions(+), 2 deletions(-)

(limited to 'servers/rendering/rasterizer_rd/shaders')

diff --git a/servers/rendering/rasterizer_rd/shaders/tonemap.glsl b/servers/rendering/rasterizer_rd/shaders/tonemap.glsl
index 524ca5e2ea..a142d263e2 100644
--- a/servers/rendering/rasterizer_rd/shaders/tonemap.glsl
+++ b/servers/rendering/rasterizer_rd/shaders/tonemap.glsl
@@ -48,6 +48,10 @@ layout(push_constant, binding = 1, std430) uniform Params {
 	float exposure;
 	float white;
 	float auto_exposure_grey;
+
+	vec2 pixel_size;
+	bool use_fxaa;
+	uint pad;
 }
 params;
 
@@ -255,16 +259,63 @@ vec3 apply_color_correction(vec3 color, sampler3D correction_tex) {
 	return texture(correction_tex, color).rgb;
 }
 
+vec3 do_fxaa(vec3 color, float exposure, vec2 uv_interp) {
+
+	const float FXAA_REDUCE_MIN = (1.0 / 128.0);
+	const float FXAA_REDUCE_MUL = (1.0 / 8.0);
+	const float FXAA_SPAN_MAX = 8.0;
+
+	vec3 rgbNW = textureLod(source_color, uv_interp + vec2(-1.0, -1.0) * params.pixel_size, 0.0).xyz * exposure;
+	vec3 rgbNE = textureLod(source_color, uv_interp + vec2(1.0, -1.0) * params.pixel_size, 0.0).xyz * exposure;
+	vec3 rgbSW = textureLod(source_color, uv_interp + vec2(-1.0, 1.0) * params.pixel_size, 0.0).xyz * exposure;
+	vec3 rgbSE = textureLod(source_color, uv_interp + vec2(1.0, 1.0) * params.pixel_size, 0.0).xyz * exposure;
+	vec3 rgbM = color;
+	vec3 luma = vec3(0.299, 0.587, 0.114);
+	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)) *
+		  params.pixel_size;
+
+	vec3 rgbA = 0.5 * (textureLod(source_color, uv_interp + dir * (1.0 / 3.0 - 0.5), 0.0).xyz * exposure + textureLod(source_color, uv_interp + dir * (2.0 / 3.0 - 0.5), 0.0).xyz) * exposure;
+	vec3 rgbB = rgbA * 0.5 + 0.25 * (textureLod(source_color, uv_interp + dir * -0.5, 0.0).xyz * exposure +
+											textureLod(source_color, uv_interp + dir * 0.5, 0.0).xyz * exposure);
+
+	float lumaB = dot(rgbB, luma);
+	if ((lumaB < lumaMin) || (lumaB > lumaMax))
+		return rgbA;
+	else
+		return rgbB;
+}
+
 void main() {
 	vec3 color = textureLod(source_color, uv_interp, 0.0f).rgb;
 
 	// Exposure
 
+	float exposure = params.exposure;
+
 	if (params.use_auto_exposure) {
-		color /= texelFetch(source_auto_exposure, ivec2(0, 0), 0).r / params.auto_exposure_grey;
+		exposure *= 1.0 / (texelFetch(source_auto_exposure, ivec2(0, 0), 0).r / params.auto_exposure_grey);
 	}
 
-	color *= params.exposure;
+	color *= exposure;
 
 	// Early Tonemap & SRGB Conversion
 
@@ -274,6 +325,9 @@ void main() {
 		color.rgb = mix(color.rgb, glow, params.glow_intensity);
 	}
 
+	if (params.use_fxaa) {
+		color = do_fxaa(color, exposure, uv_interp);
+	}
 	color = apply_tonemapping(color, params.white);
 
 	color = linear_to_srgb(color); // regular linear -> SRGB conversion
-- 
cgit v1.2.3