Fix resizing compute shaders when used with postprocessing effects.

diff --git a/effect_chain.cpp b/effect_chain.cpp
index b82102357180d2534c82018c2bc82ecfa1230019..aefae8f0c908a105457d0e2416481eda6c0a4297 100644 (file)
--- a/effect_chain.cpp
+++ b/effect_chain.cpp
@@ -1050,7 +1050,7 @@ void EffectChain::inform_input_sizes(Phase *phase)
 // desired output size might change based on the inputs.
 void EffectChain::find_output_size(Phase *phase)
 {
 // desired output size might change based on the inputs.
 void EffectChain::find_output_size(Phase *phase)
 {

-       Node *output_node = phase->effects.back();
+       Node *output_node = phase->is_compute_shader ? phase->compute_shader_node : phase->effects.back();

 
        // If the last effect explicitly sets an output size, use that.
        if (output_node->effect->changes_output_size()) {
 
        // If the last effect explicitly sets an output size, use that.
        if (output_node->effect->changes_output_size()) {

diff --git a/effect_chain_test.cpp b/effect_chain_test.cpp
index 31e8a5d996bae15c65b91aa49aba1c74009fe9c2..f37738d57208345c4afe1ab9f88d7756ec7c6bfd 100644 (file)
--- a/effect_chain_test.cpp
+++ b/effect_chain_test.cpp
@@ -1583,4 +1583,55 @@ TEST(ComputeShaderTest, ComputeThenOneToOne) {
        expect_equal(expected_data, out_data, 4, 2);
 }
 
        expect_equal(expected_data, out_data, 4, 2);
 }
 

+// A compute shader that also resizes its input, taking the upper-left pixel
+// of every 2x2 group. (The shader is hard-coded to 4x2 input for simplicity.)
+class Downscale2xComputeEffect : public Effect {
+public:
+       Downscale2xComputeEffect() {}
+       string effect_type_id() const override { return "Downscale2xComputeEffect"; }
+       bool is_compute_shader() const override { return true; }
+       string output_fragment_shader() override { return read_file("downscale2x.comp"); }
+       bool changes_output_size() const override { return true; }
+       void inform_input_size(unsigned input_num, unsigned width, unsigned height) override
+       {
+               this->width = width;
+               this->height = height;
+       }
+       void get_output_size(unsigned *width, unsigned *height,
+                            unsigned *virtual_width, unsigned *virtual_height) const override {
+                *width = *virtual_width = this->width / 2;
+                *height = *virtual_height = this->height / 2;
+        }
+
+private:
+       unsigned width, height;
+};
+
+// Even if the compute shader is not the last effect, it's the one that should decide
+// the output size of the phase.
+TEST(ComputeShaderTest, ResizingComputeThenOneToOne) {
+       float data[] = {
+               0.0f, 0.25f, 0.3f, 0.8f,
+               0.75f, 1.0f, 1.0f, 0.2f,
+       };
+       float expected_data[] = {
+               0.0f, 0.3f,
+       };
+       float out_data[2];
+       EffectChainTester tester(nullptr, 2, 1);
+       tester.add_input(data, FORMAT_GRAYSCALE, COLORSPACE_sRGB, GAMMA_LINEAR, 4, 2);
+
+       RewritingEffect<Downscale2xComputeEffect> *downscale_effect = new RewritingEffect<Downscale2xComputeEffect>();
+       tester.get_chain()->add_effect(downscale_effect);
+       tester.get_chain()->add_effect(new OneToOneEffect());
+       tester.get_chain()->add_effect(new BouncingIdentityEffect());
+       tester.run(out_data, GL_RED, COLORSPACE_sRGB, GAMMA_LINEAR);
+
+       expect_equal(expected_data, out_data, 2, 1);
+
+       Phase *phase = downscale_effect->replaced_node->containing_phase;
+       EXPECT_EQ(2, phase->output_width);
+       EXPECT_EQ(1, phase->output_height);
+}
+

 }  // namespace movit
 }  // namespace movit