X-Git-Url: https://git.sesse.net/?p=movit;a=blobdiff_plain;f=gamma_compression_effect.frag;h=a72a878c84720c1d0bc53274e429a4d7af0659ca;hp=27e014e1182bc30d1b6a0abde0a3055c75e28bf1;hb=3306a4a0d2300767eeef71ab877fdf1587d13475;hpb=6eb839737216564bcaf4645b7ebf6ea9efc2da09

diff --git a/gamma_compression_effect.frag b/gamma_compression_effect.frag
index 27e014e..a72a878 100644
--- a/gamma_compression_effect.frag
+++ b/gamma_compression_effect.frag
@@ -1,11 +1,25 @@
-// Compress to sRGB gamma curve.
+// Compress gamma curve.
+
+// Implicit uniforms:
+// uniform float PREFIX(linear_scale);
+// uniform float PREFIX(c)[5];
+// uniform float PREFIX(beta);
 
 vec4 FUNCNAME(vec2 tc) {
 	vec4 x = INPUT(tc);
 
-	x.r = texture1D(PREFIX(compression_curve_tex), x.r).x;
-	x.g = texture1D(PREFIX(compression_curve_tex), x.g).x;
-	x.b = texture1D(PREFIX(compression_curve_tex), x.b).x;
+	// We could reasonably get values outside (0.0, 1.0), but the formulas below
+	// are not valid outside that range, so clamp before we do anything else.
+	x.rgb = clamp(x.rgb, 0.0, 1.0);
+
+	vec3 a = x.rgb * PREFIX(linear_scale);
+
+	// Fourth-order polynomial approximation to pow(). See the .cpp file for details.
+	vec3 s = sqrt(x.rgb);
+	vec3 b = PREFIX(c)[0] + (PREFIX(c)[1] + (PREFIX(c)[2] + (PREFIX(c)[3] + PREFIX(c)[4] * s) * s) * s) * s;
+
+	vec3 f = vec3(greaterThan(x.rgb, vec3(PREFIX(beta))));
+	x = vec4(mix(a, b, f), x.a);
 
 	return x;
 }