From 8ee9712bae3cff206b3e3205748633edb33cbbcf Mon Sep 17 00:00:00 2001
From: "Steinar H. Gunderson" <sgunderson@bigfoot.com>
Date: Sat, 25 Nov 2017 01:58:08 +0100
Subject: [PATCH] Fix a bug where the wrong effect would be asked for compute
 shaders dimensions.

---
 effect_chain.cpp      |  2 +-
 effect_chain_test.cpp | 33 +++++++++++++++++++++++++++++++++
 mirror.comp           | 14 ++++++++++++++
 3 files changed, 48 insertions(+), 1 deletion(-)
 create mode 100644 mirror.comp

diff --git a/effect_chain.cpp b/effect_chain.cpp
index c6bac80..a4d9c86 100644
--- a/effect_chain.cpp
+++ b/effect_chain.cpp
@@ -2172,7 +2172,7 @@ void EffectChain::execute_phase(Phase *phase,
 
 	if (phase->is_compute_shader) {
 		unsigned x, y, z;
-		phase->output_node->effect->get_compute_dimensions(phase->output_width, phase->output_height, &x, &y, &z);
+		phase->compute_shader_node->effect->get_compute_dimensions(phase->output_width, phase->output_height, &x, &y, &z);
 
 		// Uniforms need to come after set_gl_state() _and_ get_compute_dimensions(),
 		// since they can be updated from there.
diff --git a/effect_chain_test.cpp b/effect_chain_test.cpp
index 551cdbc..b7877f5 100644
--- a/effect_chain_test.cpp
+++ b/effect_chain_test.cpp
@@ -1547,4 +1547,37 @@ TEST(ComputeShaderTest, Render8BitTo8Bit) {
 	expect_equal(data, out_data, 3, 2);
 }
 
+// A compute shader to mirror the inputs, in 2x2 blocks.
+class MirrorComputeEffect : public Effect {
+public:
+	MirrorComputeEffect() {}
+	string effect_type_id() const override { return "MirrorComputeEffect"; }
+	bool is_compute_shader() const override { return true; }
+	string output_fragment_shader() override { return read_file("mirror.comp"); }
+	void get_compute_dimensions(unsigned output_width, unsigned output_height,
+	                            unsigned *x, unsigned *y, unsigned *z) const override {
+		*x = output_width / 2;
+		*y = output_height / 2;
+		*z = 1;
+	}
+};
+
+TEST(ComputeShaderTest, Mirror) {
+	float data[] = {
+		0.0f, 0.25f, 0.3f, 0.8f,
+		0.75f, 1.0f, 1.0f, 0.2f,
+	};
+	float expected_data[] = {
+		0.8f, 0.3f, 0.25f, 0.0f,
+		0.2f, 1.0f, 1.0f, 0.75f,
+	};
+	float out_data[8];
+	EffectChainTester tester(data, 4, 2, FORMAT_GRAYSCALE, COLORSPACE_sRGB, GAMMA_LINEAR);
+	tester.get_chain()->add_effect(new MirrorComputeEffect());
+	tester.get_chain()->add_effect(new OneToOneEffect());
+	tester.run(out_data, GL_RED, COLORSPACE_sRGB, GAMMA_LINEAR);
+
+	expect_equal(expected_data, out_data, 4, 2);
+}
+
 }  // namespace movit
diff --git a/mirror.comp b/mirror.comp
new file mode 100644
index 0000000..d402136
--- /dev/null
+++ b/mirror.comp
@@ -0,0 +1,14 @@
+// A compute shader to mirror the inputs, in 2x2 blocks. For testing only.
+
+layout(local_size_x = 1) in;
+
+void FUNCNAME()
+{
+	ivec2 tc = ivec2(gl_GlobalInvocationID.xy) * ivec2(2, 2);
+	int offs = int(gl_NumWorkGroups.x) * 2 - 1;
+
+	OUTPUT(ivec2(offs - tc.x,     tc.y),     INPUT(NORMALIZE_TEXTURE_COORDS(vec2(tc.x,     tc.y))));
+	OUTPUT(ivec2(offs - tc.x - 1, tc.y),     INPUT(NORMALIZE_TEXTURE_COORDS(vec2(tc.x + 1, tc.y))));
+	OUTPUT(ivec2(offs - tc.x,     tc.y + 1), INPUT(NORMALIZE_TEXTURE_COORDS(vec2(tc.x,     tc.y + 1))));
+	OUTPUT(ivec2(offs - tc.x - 1, tc.y + 1), INPUT(NORMALIZE_TEXTURE_COORDS(vec2(tc.x + 1, tc.y + 1))));
+}
-- 
2.39.2