shaderir: Implement return

internal/shaderir/glsl.go

@@ -64,6 +64,21 @@ func (p *Program) Glsl() string {
 	return strings.Join(lines, "\n") + "\n"
 }
 
+func (p *Program) glslType(t *Type) string {
+	switch t.Main {
+	case None:
+		return "void"
+	case Image2D:
+		panic("not implemented")
+	case Array:
+		panic("not implemented")
+	case Struct:
+		return p.structName(t)
+	default:
+		return t.Main.Glsl()
+	}
+}
+
 func (p *Program) glslVarDecl(t *Type, varname string) string {
 	switch t.Main {
 	case None:
@@ -100,7 +115,7 @@ func (p *Program) glslFunc(f *Func) []string {
 	}
 
 	var lines []string
-	lines = append(lines, fmt.Sprintf("void %s(%s) {", f.Name, argsstr))
+	lines = append(lines, fmt.Sprintf("%s %s(%s) {", p.glslType(&f.Return), f.Name, argsstr))
 	lines = append(lines, p.glslBlock(&f.Block, f, 0, idx)...)
 	lines = append(lines, "}")
 
@@ -217,7 +232,11 @@ func (p *Program) glslBlock(b *Block, f *Func, level int, localVarIndex int) []s
 		case Break:
 			lines = append(lines, idt+"break;")
 		case Return:
-			lines = append(lines, idt+"return;")
+			if len(s.Exprs) == 0 {
+				lines = append(lines, idt+"return;")
+			} else {
+				lines = append(lines, fmt.Sprintf("%sreturn %s;", idt, glslExpr(&s.Exprs[0])))
+			}
 		case Discard:
 			lines = append(lines, idt+"discard;")
 		default:

internal/shaderir/ir_test.go

@@ -41,6 +41,13 @@ func blockStmt(block Block) Stmt {
 	}
 }
 
+func returnStmt(expr Expr) Stmt {
+	return Stmt{
+		Type:  Return,
+		Exprs: []Expr{expr},
+	}
+}
+
 func assignStmt(lhs Expr, rhs Expr) Stmt {
 	return Stmt{
 		Type:  Assign,
@@ -208,6 +215,29 @@ varying vec3 V0;`,
 				},
 			},
 			Glsl: `void F0(in float l0, in vec2 l1, in vec4 l2, inout mat2 l3, out mat4 l4) {
+}`,
+		},
+		{
+			Name: "FuncReturn",
+			Program: Program{
+				Funcs: []Func{
+					{
+						Name: "F0",
+						InParams: []Type{
+							{Main: Float},
+						},
+						Return: Type{Main: Float},
+						Block: block(
+							nil,
+							returnStmt(
+								varNameExpr(Local, 0),
+							),
+						),
+					},
+				},
+			},
+			Glsl: `float F0(in float l0) {
+	return l0;
 }`,
 		},
 		{

internal/shaderir/program.go

@@ -33,6 +33,7 @@ type Func struct {
 	InParams    []Type
 	InOutParams []Type
 	OutParams   []Type
+	Return      Type
 	Block       Block
 }