From 8603393928bcbfd3c6fb91497afcf22eb97be7ad Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jo=C3=A3o=20Capucho?= <jcapucho7@gmail.com>
Date: Wed, 9 Jun 2021 11:04:42 +0100
Subject: [PATCH] [glsl-in] Add collatz shader and test quad shader

---
 tests/in/glsl/246-collatz.comp | 34 ++++++++++++++++++++++++++++++++++
 tests/out/quad-glsl.wgsl       | 10 ++++++----
 2 files changed, 40 insertions(+), 4 deletions(-)
 create mode 100644 tests/in/glsl/246-collatz.comp

diff --git a/tests/in/glsl/246-collatz.comp b/tests/in/glsl/246-collatz.comp
new file mode 100644
index 0000000000..274cdca1c3
--- /dev/null
+++ b/tests/in/glsl/246-collatz.comp
@@ -0,0 +1,34 @@
+// AUTHOR: Unknown
+// ISSUE: #246
+// NOTE: Taken from the wgpu repo
+#version 450
+layout(local_size_x = 1) in;
+
+layout(set = 0, binding = 0) buffer PrimeIndices {
+    uint[] indices;
+}; // this is used as both input and output for convenience
+
+// The Collatz Conjecture states that for any integer n:
+// If n is even, n = n/2
+// If n is odd, n = 3n+1
+// And repeat this process for each new n, you will always eventually reach 1.
+// Though the conjecture has not been proven, no counterexample has ever been found.
+// This function returns how many times this recurrence needs to be applied to reach 1.
+uint collatz_iterations(uint n) {
+    uint i = 0;
+    while(n != 1) {
+        if (mod(n, 2) == 0) {
+            n = n / 2;
+        }
+        else {
+            n = (3 * n) + 1;
+        }
+        i++;
+    }
+    return i;
+}
+
+void main() {
+    uint index = gl_GlobalInvocationID.x;
+    indices[index] = collatz_iterations(indices[index]);
+}
diff --git a/tests/out/quad-glsl.wgsl b/tests/out/quad-glsl.wgsl
index fccd8cc2ab..6be3e0caa3 100644
--- a/tests/out/quad-glsl.wgsl
+++ b/tests/out/quad-glsl.wgsl
@@ -7,6 +7,7 @@ struct FragmentOutput {
     [[location(0), interpolate(perspective)]] member2: vec4<f32>;
 };
 
+var<private> c_scale: f32;
 var<private> a_pos: vec2<f32>;
 var<private> a_uv: vec2<f32>;
 var<private> v_uv: vec2<f32>;
@@ -15,10 +16,11 @@ var<private> v_uv1: vec2<f32>;
 var<private> o_color: vec4<f32>;
 
 fn vert_main() {
-    let _e2: vec2<f32> = a_pos;
-    let _e4: vec2<f32> = a_uv;
-    v_uv = _e4;
-    gl_Position = vec4<f32>((1.2000000476837158 * _e2), 0.0, 1.0);
+    let _e1: f32 = c_scale;
+    let _e3: vec2<f32> = a_pos;
+    let _e5: vec2<f32> = a_uv;
+    v_uv = _e5;
+    gl_Position = vec4<f32>((_e1 * _e3), 0.0, 1.0);
     return;
 }