shader: Enable more Go syntax

examples/shader/main.go

@@ -29,6 +29,8 @@ const (
 
 const shaderSrc = `package main
 
+var Time float
+
 // viewportSize is a predefined function.
 
 func Vertex(position vec2, texCoord vec2, color vec4) vec4 {
@@ -41,14 +43,22 @@ func Vertex(position vec2, texCoord vec2, color vec4) vec4 {
 }
 
 func Fragment(position vec4) vec4 {
-	return vec4(position.x/viewportSize().x, position.y/viewportSize().y, 0, 1)
+	pos := position.xy / viewportSize()
+	color := 0.0
+	color += sin(pos.x * cos(Time / 15.0) * 80.0) + cos(pos.y * cos(Time / 15.0) * 10.0)
+	color += sin(pos.y * sin(Time / 10.0) * 40.0) + cos(pos.x * sin(Time / 25.0) * 40.0)
+	color += sin(pos.x * sin(Time / 5.0) * 10.0) + sin(pos.y * sin(Time / 35.0) * 80.0)
+	color *= sin(Time / 10.0) * 0.5
+	return vec4(color, color * 0.5, sin(color + Time / 3.0 ) * 0.75, 1.0)
 }`
 
 type Game struct {
 	shader *ebiten.Shader
+	time   int
 }
 
 func (g *Game) Update(screen *ebiten.Image) error {
+	g.time++
 	if g.shader == nil {
 		var err error
 		g.shader, err = ebiten.NewShader([]byte(shaderSrc))
@@ -80,7 +90,12 @@ func (g *Game) Draw(screen *ebiten.Image) {
 		},
 	}
 	is := []uint16{0, 1, 2, 1, 2, 3}
-	screen.DrawTrianglesWithShader(vs, is, g.shader, nil)
+
+	op := &ebiten.DrawTrianglesWithShaderOptions{}
+	op.Uniforms = []interface{}{
+		float32(g.time) / 60, // time
+	}
+	screen.DrawTrianglesWithShader(vs, is, g.shader, op)
 }
 
 func (g *Game) Layout(outsideWidth, outsideHeight int) (int, int) {

internal/graphicsdriver/opengl/program.go

@@ -285,7 +285,7 @@ func (g *Graphics) useProgram(program program, uniforms []uniformVariable) error
 			}
 			g.context.bindTexture(v)
 		default:
-			return fmt.Errorf("opengl: unexpected uniform value: %v", u.value)
+			return fmt.Errorf("opengl: unexpected uniform value: %v (type: %T)", u.value, u.value)
 		}
 	}
 	return nil

internal/shader/shader.go

@@ -557,7 +557,9 @@ func (cs *compileState) parseBlock(outer *block, b *ast.BlockStmt, inParams, out
 						if len(ts) > 1 {
 							cs.addError(l.Pos(), fmt.Sprintf("single-value context and multiple-value context cannot be mixed"))
 						}
-						v.typ = ts[0]
+						if len(ts) == 1 {
+							v.typ = ts[0]
+						}
 					} else {
 						if i == 0 {
 							rhsTypes = cs.detectType(block, l.Rhs[0])
@@ -578,6 +580,40 @@ func (cs *compileState) parseBlock(outer *block, b *ast.BlockStmt, inParams, out
 					return nil
 				}
 				cs.assign(block, l.Pos(), l.Lhs, l.Rhs)
+			case token.ADD_ASSIGN, token.SUB_ASSIGN, token.MUL_ASSIGN, token.QUO_ASSIGN, token.REM_ASSIGN:
+				var op shaderir.Op
+				switch l.Tok {
+				case token.ADD_ASSIGN:
+					op = shaderir.Add
+				case token.SUB_ASSIGN:
+					op = shaderir.Sub
+				case token.MUL_ASSIGN:
+					op = shaderir.Mul
+				case token.QUO_ASSIGN:
+					op = shaderir.Div
+				case token.REM_ASSIGN:
+					op = shaderir.ModOp
+				}
+				rhs, stmts := cs.parseExpr(block, l.Rhs[0])
+				block.ir.Stmts = append(block.ir.Stmts, stmts...)
+				lhs, stmts := cs.parseExpr(block, l.Lhs[0])
+				block.ir.Stmts = append(block.ir.Stmts, stmts...)
+				block.ir.Stmts = append(block.ir.Stmts, shaderir.Stmt{
+					Type: shaderir.Assign,
+					Exprs: []shaderir.Expr{
+						lhs[0],
+						{
+							Type: shaderir.Binary,
+							Op:   op,
+							Exprs: []shaderir.Expr{
+								lhs[0],
+								rhs[0],
+							},
+						},
+					},
+				})
+			default:
+				cs.addError(l.Pos(), fmt.Sprintf("unexpected token: %s", l.Tok))
 			}
 		case *ast.BlockStmt:
 			b := cs.parseBlock(block, l, nil, nil)

internal/shader/type.go

@@ -72,6 +72,30 @@ func (cs *compileState) detectType(b *block, expr ast.Expr) []shaderir.Type {
 		}
 		cs.addError(expr.Pos(), fmt.Sprintf("unexpected literal: %s", e.Value))
 		return nil
+	case *ast.BinaryExpr:
+		t1, t2 := cs.detectType(b, e.X), cs.detectType(b, e.Y)
+		if len(t1) != 1 || len(t2) != 1 {
+			cs.addError(expr.Pos(), fmt.Sprintf("binary operator cannot be used for multiple-value context: %v", expr))
+			return nil
+		}
+		if !t1[0].Equal(&t2[0]) {
+			// TODO: Move this checker to shaderir
+			if t1[0].Main == shaderir.Float {
+				switch t2[0].Main {
+				case shaderir.Vec2, shaderir.Vec3, shaderir.Vec4:
+					return t2
+				}
+			}
+			if t2[0].Main == shaderir.Float {
+				switch t1[0].Main {
+				case shaderir.Vec2, shaderir.Vec3, shaderir.Vec4:
+					return t1
+				}
+			}
+			cs.addError(expr.Pos(), fmt.Sprintf("types between a binary operator don't match"))
+			return nil
+		}
+		return t1
 	case *ast.CallExpr:
 		n := e.Fun.(*ast.Ident).Name
 		f, ok := shaderir.ParseBuiltinFunc(n)
@@ -127,8 +151,34 @@ func (cs *compileState) detectType(b *block, expr ast.Expr) []shaderir.Type {
 		}
 		cs.addError(expr.Pos(), fmt.Sprintf("unexpected identifier: %s", n))
 		return nil
-	//case *ast.SelectorExpr:
+	case *ast.SelectorExpr:
-	//return fmt.Sprintf("%cs.%s", dumpExpr(e.X), dumpExpr(e.Sel))
+		t := cs.detectType(b, e.X)
+		if len(t) != 1 {
+			cs.addError(expr.Pos(), fmt.Sprintf("selector is not available in multiple-value context: %v", e.X))
+			return nil
+		}
+		switch t[0].Main {
+		case shaderir.Vec2, shaderir.Vec3, shaderir.Vec4:
+			switch len(e.Sel.Name) {
+			case 1:
+				return []shaderir.Type{{Main: shaderir.Float}}
+			case 2:
+				return []shaderir.Type{{Main: shaderir.Vec2}}
+			case 3:
+				return []shaderir.Type{{Main: shaderir.Float}}
+			case 4:
+				return []shaderir.Type{{Main: shaderir.Float}}
+			default:
+				cs.addError(expr.Pos(), fmt.Sprintf("invalid selector: %s", e.Sel.Name))
+			}
+			return nil
+		case shaderir.Struct:
+			cs.addError(expr.Pos(), fmt.Sprintf("selector for a struct is not implemented yet"))
+			return nil
+		default:
+			cs.addError(expr.Pos(), fmt.Sprintf("selector is not available for: %v", expr))
+			return nil
+		}
 	default:
 		cs.addError(expr.Pos(), fmt.Sprintf("detecting type not implemented: %#v", expr))
 		return nil

internal/shaderir/type.go

@@ -25,6 +25,24 @@ type Type struct {
 	Length int
 }
 
+func (t *Type) Equal(rhs *Type) bool {
+	if t.Main != rhs.Main {
+		return false
+	}
+	if t.Length != rhs.Length {
+		return false
+	}
+	if len(t.Sub) != len(rhs.Sub) {
+		return false
+	}
+	for i, s := range t.Sub {
+		if !s.Equal(&rhs.Sub[i]) {
+			return false
+		}
+	}
+	return true
+}
+
 func (t *Type) serialize() string {
 	switch t.Main {
 	case None: