From aef00a5235c430a2d582ea808aea16e557b948ea Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Sun, 27 Mar 2022 01:22:50 +0900
Subject: [PATCH] internal/shader: bug fix: wrong type deduction at
 (scalar)*(matrix)

Updates #2037
---
 internal/shader/expr.go | 2 +-
 shader_test.go          | 6 ++++--
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/internal/shader/expr.go b/internal/shader/expr.go
index c03370f23..f53aff37d 100644
--- a/internal/shader/expr.go
+++ b/internal/shader/expr.go
@@ -232,7 +232,7 @@ func (cs *compileState) parseExpr(block *block, expr ast.Expr, markLocalVariable
 					cs.addError(e.Pos(), fmt.Sprintf("types don't match: %s %s %s", lhst.String(), e.Op, rhst.String()))
 					return nil, nil, nil, false
 				}
-				t = lhst
+				t = rhst
 			default:
 				cs.addError(e.Pos(), fmt.Sprintf("types don't match: %s %s %s", lhst.String(), e.Op, rhst.String()))
 				return nil, nil, nil, false
diff --git a/shader_test.go b/shader_test.go
index e301356d6..ec4341cab 100644
--- a/shader_test.go
+++ b/shader_test.go
@@ -734,9 +734,10 @@ func TestShaderUniformMatrix2(t *testing.T) {
 	s, err := ebiten.NewShader([]byte(`package main
 
 var Mat2 mat2
+var F float
 
 func Fragment(position vec4, texCoord vec2, color vec4) vec4 {
-	return vec4(Mat2 * vec2(1), 1, 1)
+	return vec4(F * Mat2 * vec2(1), 1, 1)
 }
 `))
 	if err != nil {
@@ -749,13 +750,14 @@ func Fragment(position vec4, texCoord vec2, color vec4) vec4 {
 			1.0 / 256.0, 2.0 / 256.0,
 			3.0 / 256.0, 4.0 / 256.0,
 		},
+		"F": float32(2),
 	}
 	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{4, 6, 0xff, 0xff}
+			want := color.RGBA{8, 12, 0xff, 0xff}
 			if !sameColors(got, want, 2) {
 				t.Errorf("dst.At(%d, %d): got: %v, want: %v", i, j, got, want)
 			}