diff --git a/internal/shaderir/glsl.go b/internal/shaderir/glsl.go
index 16c0354b9..eeabb5e6d 100644
--- a/internal/shaderir/glsl.go
+++ b/internal/shaderir/glsl.go
@@ -119,8 +119,8 @@ func (p *Program) glslBlock(b *Block, f *Func, level int, localVarIndex int) []s
 	var glslExpr func(e *Expr) string
 	glslExpr = func(e *Expr) string {
 		switch e.Type {
-		case Literal:
-			return e.Value
+		case Numeric:
+			return fmt.Sprintf("%.9e", e.Num)
 		case VarName:
 			switch e.Variable.Type {
 			case Uniform:
@@ -135,7 +135,7 @@ func (p *Program) glslBlock(b *Block, f *Func, level int, localVarIndex int) []s
 				return fmt.Sprintf("?(unexpected variable type: %d)", e.Variable.Type)
 			}
 		case Ident:
-			return e.Value
+			return e.Ident
 		case Unary:
 			return fmt.Sprintf("%s(%s)", e.Op, glslExpr(&e.Exprs[0]))
 		case Binary:
@@ -163,7 +163,13 @@ func (p *Program) glslBlock(b *Block, f *Func, level int, localVarIndex int) []s
 		case Assign:
 			lines = append(lines, fmt.Sprintf("%s%s = %s;", idt, glslExpr(&s.Exprs[0]), glslExpr(&s.Exprs[1])))
 		case If:
-			panic("not implemented")
+			lines = append(lines, fmt.Sprintf("%sif (%s) {", idt, glslExpr(&s.Exprs[0])))
+			lines = append(lines, p.glslBlock(s.Block, f, level+1, localVarIndex)...)
+			if s.ElseBlock != nil {
+				lines = append(lines, fmt.Sprintf("%s} else {", idt))
+				lines = append(lines, p.glslBlock(s.ElseBlock, f, level+1, localVarIndex)...)
+			}
+			lines = append(lines, fmt.Sprintf("%s}", idt))
 		case For:
 			panic("not implemented")
 		case Continue:
diff --git a/internal/shaderir/ir_test.go b/internal/shaderir/ir_test.go
index ed34acb9b..9b79aea7e 100644
--- a/internal/shaderir/ir_test.go
+++ b/internal/shaderir/ir_test.go
@@ -27,6 +27,22 @@ func assignStmt(lhs Expr, rhs Expr) Stmt {
 	}
 }
 
+func ifStmt(cond Expr, block *Block, elseBlock *Block) Stmt {
+	return Stmt{
+		Type:      If,
+		Exprs:     []Expr{cond},
+		Block:     block,
+		ElseBlock: elseBlock,
+	}
+}
+
+func numericExpr(value float64) Expr {
+	return Expr{
+		Type: Numeric,
+		Num:  value,
+	}
+}
+
 func varNameExpr(vt VariableType, index int) Expr {
 	return Expr{
 		Type: VarName,
@@ -224,7 +240,8 @@ varying vec3 V0;`,
 							Stmts: []Stmt{
 								assignStmt(
 									varNameExpr(Local, 2),
-									binaryExpr(Add,
+									binaryExpr(
+										Add,
 										varNameExpr(Local, 0),
 										varNameExpr(Local, 1),
 									),
@@ -236,6 +253,57 @@ varying vec3 V0;`,
 			},
 			Glsl: `void F0(in float l0, in float l1, out float l2) {
 	l2 = (l0) + (l1);
+}`,
+		},
+		{
+			Name: "FuncIf",
+			Program: Program{
+				Funcs: []Func{
+					{
+						Name: "F0",
+						InParams: []Type{
+							{Main: Float},
+							{Main: Float},
+						},
+						OutParams: []Type{
+							{Main: Float},
+						},
+						Block: Block{
+							Stmts: []Stmt{
+								ifStmt(
+									binaryExpr(
+										Eq,
+										varNameExpr(Local, 0),
+										numericExpr(0),
+									),
+									&Block{
+										Stmts: []Stmt{
+											assignStmt(
+												varNameExpr(Local, 2),
+												varNameExpr(Local, 0),
+											),
+										},
+									},
+									&Block{
+										Stmts: []Stmt{
+											assignStmt(
+												varNameExpr(Local, 2),
+												varNameExpr(Local, 1),
+											),
+										},
+									},
+								),
+							},
+						},
+					},
+				},
+			},
+			Glsl: `void F0(in float l0, in float l1, out float l2) {
+	if ((l0) == (0.000000000e+00)) {
+		l2 = l0;
+	} else {
+		l2 = l1;
+	}
 }`,
 		},
 	}
diff --git a/internal/shaderir/program.go b/internal/shaderir/program.go
index 16a96685c..7888c043b 100644
--- a/internal/shaderir/program.go
+++ b/internal/shaderir/program.go
@@ -42,11 +42,10 @@ type Block struct {
 type Stmt struct {
 	Type      StmtType
 	Exprs     []Expr
-	Condition Expr
-	ElseExprs []Expr
+	Block     *Block
+	ElseBlock *Block
 	ForInit   Expr
 	ForRest   Expr
-	Block     *Block
 }
 
 type StmtType int
@@ -67,14 +66,15 @@ type Expr struct {
 	Type     ExprType
 	Exprs    []Expr
 	Variable Variable
-	Value    string
+	Num      float64
+	Ident    string
 	Op       Op
 }
 
 type ExprType int
 
 const (
-	Literal ExprType = iota
+	Numeric ExprType = iota
 	VarName
 	Ident
 	Unary