Try to adjust the mip levels to get box blur for free as needed.

[movit] / gamma_compression_effect.cpp

diff --git a/gamma_compression_effect.cpp b/gamma_compression_effect.cpp
index 69d24937bb18e4250fd377a1e88edcd58953403f..945267ceb5225ecebd616262dd14399ad1e7a4c2 100644 (file)
--- a/gamma_compression_effect.cpp
+++ b/gamma_compression_effect.cpp
@@ -1,3 +1,4 @@
+#include <math.h>
 #include <assert.h>
 
 #include "gamma_compression_effect.h"
@@ -7,18 +8,37 @@ GammaCompressionEffect::GammaCompressionEffect()
        : destination_curve(GAMMA_LINEAR)
 {
        register_int("destination_curve", (int *)&destination_curve);
+       register_1d_texture("compression_curve_tex", compression_curve, COMPRESSION_CURVE_SIZE);
 }
 
 std::string GammaCompressionEffect::output_fragment_shader()
 {
-       switch (destination_curve) {
-       case GAMMA_LINEAR:
+       if (destination_curve == GAMMA_LINEAR) {
                return read_file("identity.frag");
-       case GAMMA_sRGB:
-               return read_file("gamma_compression_effect_srgb.frag");
-       case GAMMA_REC_709:  // and GAMMA_REC_601
-               return read_file("gamma_compression_effect_rec709.frag");
-       default:
-               assert(false);
        }
+       if (destination_curve == GAMMA_sRGB) {
+               for (unsigned i = 0; i < COMPRESSION_CURVE_SIZE; ++i) {
+                       float x = i / (float)(COMPRESSION_CURVE_SIZE - 1);
+                       if (x < 0.0031308f) {
+                               compression_curve[i] = 12.92f * x;
+                       } else {
+                               compression_curve[i] = 1.055f * pow(x, 1.0f / 2.4f) - 0.055f;
+                       }
+               }
+               invalidate_1d_texture("compression_curve_tex");
+               return read_file("gamma_compression_effect.frag");
+       }
+       if (destination_curve == GAMMA_REC_709) {  // And Rec. 601.
+               for (unsigned i = 0; i < COMPRESSION_CURVE_SIZE; ++i) {
+                       float x = i / (float)(COMPRESSION_CURVE_SIZE - 1);
+                       if (x < 0.018f) {
+                               compression_curve[i] = 4.5f * x;
+                       } else {
+                               compression_curve[i] = 1.099f * pow(x, 0.45f) - 0.099;
+                       }
+               }
+               invalidate_1d_texture("compression_curve_tex");
+               return read_file("gamma_compression_effect.frag");
+       }
+       assert(false);
 }