In OverlayEffect, add support for swapping the inputs.

diff --git a/overlay_effect.cpp b/overlay_effect.cpp
index 3a42240a0b063914292cff2fa65f0de62c8ea4c8..3440f76bf6a5a415325c0b7eb9af7cd15c20b48d 100644 (file)
--- a/overlay_effect.cpp
+++ b/overlay_effect.cpp
@@ -5,11 +5,17 @@ using namespace std;
 
 namespace movit {
 
-OverlayEffect::OverlayEffect() {}
+OverlayEffect::OverlayEffect()
+       : swap_inputs(false)
+{
+       register_int("swap_inputs", (int *)&swap_inputs);
+}
 
 string OverlayEffect::output_fragment_shader()
 {
-       return read_file("overlay_effect.frag");
+       char buf[256];
+       snprintf(buf, sizeof(buf), "#define SWAP_INPUTS %d\n", swap_inputs);
+       return buf + read_file("overlay_effect.frag");
 }
 
 }  // namespace movit

diff --git a/overlay_effect.frag b/overlay_effect.frag
index 9e5709d1dad6271535701316d4ff1b60c4533d99..d32cc062204c4492dbb552c6930908e2f8b805be 100644 (file)
--- a/overlay_effect.frag
+++ b/overlay_effect.frag
@@ -13,7 +13,15 @@
 // C_o without the division by alpha_o).
 
 vec4 FUNCNAME(vec2 tc) {
+// SWAP_INPUTS will be #defined to 1 if we want to swap the two inputs,
+#if SWAP_INPUTS
+       vec4 bottom = INPUT2(tc);
+       vec4 top = INPUT1(tc);
+#else
        vec4 bottom = INPUT1(tc);
        vec4 top = INPUT2(tc);
+#endif
        return top + (1.0 - top.a) * bottom;
 }
+
+#undef SWAP_INPUTS

diff --git a/overlay_effect.h b/overlay_effect.h
index c11569f4eec6c34e0eea4e169ee51b6142fef637..40a6fff99e2a465f71cff654d8ae675495c08685 100644 (file)
--- a/overlay_effect.h
+++ b/overlay_effect.h
@@ -32,6 +32,11 @@ public:
        // However, understanding that would require changes
        // to EffectChain, so postpone that optimization for later.
        virtual AlphaHandling alpha_handling() const { return INPUT_PREMULTIPLIED_ALPHA_KEEP_BLANK; }
+
+private:
+       // If true, overlays input1 on top of input2 instead of vice versa.
+       // Must be set before finalize.
+       bool swap_inputs;
 };
 
 }  // namespace movit

diff --git a/overlay_effect_test.cpp b/overlay_effect_test.cpp
index dfda93f368db830d7833b7384fc7239b1418ae84..3f7ffd3e97229b15aa42cf85ba774593b2e6c422 100644 (file)
--- a/overlay_effect_test.cpp
+++ b/overlay_effect_test.cpp
@@ -8,27 +8,36 @@
 #include "input.h"
 #include "overlay_effect.h"
 #include "test_util.h"
+#include "util.h"
 
 namespace movit {
 
 TEST(OverlayEffectTest, TopDominatesBottomWhenNoAlpha) {
-       float data_a[] = {
-               0.0f, 0.25f,
-               0.75f, 1.0f,
-       };
-       float data_b[] = {
-               1.0f, 0.5f,
-               0.75f, 0.6f,
-       };
-       float out_data[4];
-       EffectChainTester tester(data_a, 2, 2, FORMAT_GRAYSCALE, COLORSPACE_sRGB, GAMMA_LINEAR);
-       Effect *input1 = tester.get_chain()->last_added_effect();
-       Effect *input2 = tester.add_input(data_b, FORMAT_GRAYSCALE, COLORSPACE_sRGB, GAMMA_LINEAR);
-
-       tester.get_chain()->add_effect(new OverlayEffect(), input1, input2);
-       tester.run(out_data, GL_RED, COLORSPACE_sRGB, GAMMA_LINEAR);
-
-       expect_equal(data_b, out_data, 2, 2);
+       for (int swap_inputs = 0; swap_inputs < 2; ++swap_inputs) {  // false, true.
+               float data_a[] = {
+                       0.0f, 0.25f,
+                       0.75f, 1.0f,
+               };
+               float data_b[] = {
+                       1.0f, 0.5f,
+                       0.75f, 0.6f,
+               };
+               float out_data[4];
+               EffectChainTester tester(data_a, 2, 2, FORMAT_GRAYSCALE, COLORSPACE_sRGB, GAMMA_LINEAR);
+               Effect *input1 = tester.get_chain()->last_added_effect();
+               Effect *input2 = tester.add_input(data_b, FORMAT_GRAYSCALE, COLORSPACE_sRGB, GAMMA_LINEAR);
+
+               OverlayEffect *effect = new OverlayEffect();
+               CHECK(effect->set_int("swap_inputs", swap_inputs));
+               tester.get_chain()->add_effect(effect, input1, input2);
+               tester.run(out_data, GL_RED, COLORSPACE_sRGB, GAMMA_LINEAR);
+
+               if (swap_inputs) {
+                       expect_equal(data_a, out_data, 2, 2);
+               } else {
+                       expect_equal(data_b, out_data, 2, 2);
+               }
+       }
 }
 
 TEST(OverlayEffectTest, BottomDominatesTopWhenTopIsTransparent) {