From b96b75d51ca73a8969ae75fc1edb039007e77b68 Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Sat, 26 Mar 2022 01:19:20 +0900
Subject: [PATCH] ebiten: add TestShaderMatrixInitialize

---
 shader_test.go | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/shader_test.go b/shader_test.go
index 271a88a88..c087732cf 100644
--- a/shader_test.go
+++ b/shader_test.go
@@ -593,3 +593,35 @@ func Fragment(position vec4, texCoord vec2, color vec4) vec4 {
 		}
 	}
 }
+
+func TestShaderMatrixInitialize(t *testing.T) {
+	const w, h = 16, 16
+
+	src := ebiten.NewImage(w, h)
+	src.Fill(color.RGBA{0x10, 0x20, 0x30, 0xff})
+
+	dst := ebiten.NewImage(w, h)
+	s, err := ebiten.NewShader([]byte(`package main
+
+func Fragment(position vec4, texCoord vec2, color vec4) vec4 {
+	return mat4(2) * imageSrc0At(texCoord);
+}
+`))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	op := &ebiten.DrawRectShaderOptions{}
+	op.Images[0] = src
+	dst.DrawRectShader(w, h, s, op)
+
+	for j := 0; j < h; j++ {
+		for i := 0; i < w; i++ {
+			got := dst.At(i, j).(color.RGBA)
+			want := color.RGBA{0x20, 0x40, 0x60, 0xff}
+			if !sameColors(got, want, 2) {
+				t.Errorf("dst.At(%d, %d): got: %v, want: %v", i, j, got, want)
+			}
+		}
+	}
+}