From 796165492768da892ce897c57b66fbd4c43b640e Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Sun, 20 Nov 2022 23:14:09 +0900
Subject: [PATCH] internal/graphicsdriver/metal: bug fix: wrong alignment for
 vec3

---
 .../graphicsdriver/metal/graphics_darwin.go   | 13 +++++++
 shader_test.go                                | 36 +++++++++++++++++++
 2 files changed, 49 insertions(+)

diff --git a/internal/graphicsdriver/metal/graphics_darwin.go b/internal/graphicsdriver/metal/graphics_darwin.go
index d2dfaa5e8..9a3e456bc 100644
--- a/internal/graphicsdriver/metal/graphics_darwin.go
+++ b/internal/graphicsdriver/metal/graphics_darwin.go
@@ -576,6 +576,11 @@ func (g *Graphics) DrawTriangles(dstID graphicsdriver.ImageID, srcIDs [graphics.
 
 		t := g.shaders[shaderID].ir.Uniforms[i]
 		switch t.Main {
+		case shaderir.Vec3:
+			// float3x3 requires 16-byte alignment (#2463).
+			v1 := make([]uint32, 4)
+			copy(v1[0:3], v[0:3])
+			uniformVars[i] = v1
 		case shaderir.Mat3:
 			// float3x3 requires 16-byte alignment (#2036).
 			v1 := make([]uint32, 12)
@@ -585,6 +590,14 @@ func (g *Graphics) DrawTriangles(dstID graphicsdriver.ImageID, srcIDs [graphics.
 			uniformVars[i] = v1
 		case shaderir.Array:
 			switch t.Sub[0].Main {
+			case shaderir.Vec3:
+				v1 := make([]uint32, t.Length*4)
+				for j := 0; j < t.Length; j++ {
+					offset0 := j * 3
+					offset1 := j * 4
+					copy(v1[offset1:offset1+3], v[offset0:offset0+3])
+				}
+				uniformVars[i] = v1
 			case shaderir.Mat3:
 				v1 := make([]uint32, t.Length*12)
 				for j := 0; j < t.Length; j++ {
diff --git a/shader_test.go b/shader_test.go
index 6050d22f5..452a20d0c 100644
--- a/shader_test.go
+++ b/shader_test.go
@@ -1406,3 +1406,39 @@ func Fragment(position vec4, texCoord vec2, color vec4) vec4 {
 		})
 	}
 }
+
+// Issue #2463
+func TestShaderVec3Array(t *testing.T) {
+	const shader = `package main
+
+var U [4]vec3
+
+func Fragment(position vec4, texCoord vec2, color vec4) vec4 {
+	return vec4(U[0].x/255.0, U[1].y/255.0, U[2].z/255.0, U[3].x/255.0)
+}
+`
+	const w, h = 1, 1
+
+	dst := ebiten.NewImage(w, h)
+	defer dst.Dispose()
+
+	s, err := ebiten.NewShader([]byte(shader))
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer s.Dispose()
+
+	op := &ebiten.DrawRectShaderOptions{}
+	op.Uniforms = map[string]any{
+		"U": []float32{
+			0x24, 0x3f, 0x6a,
+			0x88, 0x85, 0xa3,
+			0x08, 0xd3, 0x13,
+			0x19, 0x8a, 0x2e,
+		},
+	}
+	dst.DrawRectShader(w, h, s, op)
+	if got, want := dst.At(0, 0).(color.RGBA), (color.RGBA{0x24, 0x85, 0x13, 0x19}); !sameColors(got, want, 1) {
+		t.Errorf("got: %v, want: %v", got, want)
+	}
+}