Fix an issue where a (cached) shader program could be used from multiple

[movit] / lift_gamma_gain_effect.frag

diff --git a/lift_gamma_gain_effect.frag b/lift_gamma_gain_effect.frag
index 80e04d0659d52969bc287ffa3d96dca4010e129d..7342d7505eb53da6e66167b4921138ef2f5a68dc 100644 (file)
--- a/lift_gamma_gain_effect.frag
+++ b/lift_gamma_gain_effect.frag
@@ -1,21 +1,22 @@
-// Standard lift/gamma/gain color correction tools.
+// Implicit uniforms:
 //
-// We do lift in a nonlinear (gamma-2.2) space since that looks a lot better
-// than in linear (blacks stay a lot closer to black). The two others don't
-// really care; they are (sans some constants) commutative with the x^2.2
-// operation.
-
 // These are calculated in the host code to save some arithmetic.
-uniform vec3 PREFIX(gain_pow_inv_gamma);  // gain^(1/gamma).
-uniform vec3 PREFIX(inv_gamma_22);  // 2.2 / gamma.
+// uniform vec3 PREFIX(gain_pow_inv_gamma);  // gain^(1/gamma).
+// uniform vec3 PREFIX(inv_gamma_22);  // 2.2 / gamma.
 
 vec4 FUNCNAME(vec2 tc) {
-       vec4 x = LAST_INPUT(tc);
+       vec4 x = INPUT(tc);
+
+       x.rgb /= x.aaa;
+
+       // pow() of negative numbers is undefined, so clip out-of-gamut values.
+       x.rgb = max(x.rgb, 0.0);
 
        x.rgb = pow(x.rgb, vec3(1.0/2.2));
        x.rgb += PREFIX(lift) * (vec3(1) - x.rgb);
        x.rgb = pow(x.rgb, PREFIX(inv_gamma_22));
        x.rgb *= PREFIX(gain_pow_inv_gamma);
+       x.rgb *= x.aaa;
 
        return x;
 }