Add basic tonemapping

After some experimentation for now go with the tried-and-true filmic
option. Needed to tweak the lighting a little bit for that, and also fix
the specular that was not taking sun intensity into account.

src/shaders/final.comp.glsl

@@ -61,12 +61,12 @@ void main()
 	if (shadeData.shadowsEnabled == 1)
 		shadow = texture(shadowImage, uv).r;
 
-	float ambient = 0.03;
-	float shadowAmbient = 0.03;
-	float sunIntensity = 1.5;
+	float ambient = 0.07;
+	float shadowAmbient = 0.05;
+	float sunIntensity = 2.5;
 
-	vec3 outputColor = albedo.rgb * (ndotl * min(shadow + shadowAmbient, 1.0) * sunIntensity + ambient) + vec3(specular * shadow) + emissive;
+	vec3 outputColor = albedo.rgb * (ndotl * min(shadow + shadowAmbient, 1.0) * sunIntensity + ambient) + vec3(specular * shadow) * sunIntensity + emissive;
 
 	float deband = gradientNoise(vec2(pos)) * 2 - 1;
-	imageStore(outImage, ivec2(pos), vec4(tosrgb(outputColor) + deband * (0.5 / 255), 1.0));
+	imageStore(outImage, ivec2(pos), vec4(tonemap(outputColor) + deband * (0.5 / 255), 1.0));
 }

src/shaders/math.h

@@ -69,6 +69,14 @@ vec4 fromsrgb(vec4 c)
 	return vec4(pow(c.xyz, vec3(2.2)), c.w);
 }
 
+// Optimized filmic operator by Jim Hejl and Richard Burgess-Dawson
+// http://filmicworlds.com/blog/filmic-tonemapping-operators/
+vec3 tonemap(vec3 c)
+{
+	vec3 x = max(vec3(0), c - 0.004);
+	return (x * (6.2 * x + .5)) / (x * (6.2 * x + 1.7) + 0.06);
+}
+
 // Gradient noise from Jorge Jimenez's presentation:
 // http://www.iryoku.com/next-generation-post-processing-in-call-of-duty-advanced-warfare
 float gradientNoise(vec2 uv)