diff --git a/internal/shaderir/glsl.go b/internal/shaderir/glsl.go
index f24657ed7..0d2822cfe 100644
--- a/internal/shaderir/glsl.go
+++ b/internal/shaderir/glsl.go
@@ -188,6 +188,8 @@ func (p *Program) glslBlock(b *Block, level int, localVarIndex int) []string {
 			default:
 				return fmt.Sprintf("?(unexpected variable type: %d)", e.Variable.Type)
 			}
+		case BuiltinFuncExpr:
+			return string(e.BuiltinFunc)
 		case Ident:
 			return e.Ident
 		case Unary:
@@ -205,10 +207,10 @@ func (p *Program) glslBlock(b *Block, level int, localVarIndex int) []string {
 			return fmt.Sprintf("(%s) ? (%s) : (%s)", glslExpr(&e.Exprs[0]), glslExpr(&e.Exprs[1]), glslExpr(&e.Exprs[2]))
 		case Call:
 			var args []string
-			for _, exp := range e.Exprs {
+			for _, exp := range e.Exprs[1:] {
 				args = append(args, glslExpr(&exp))
 			}
-			return fmt.Sprintf("%s(%s)", e.Ident, strings.Join(args, ", "))
+			return fmt.Sprintf("(%s)(%s)", glslExpr(&e.Exprs[0]), strings.Join(args, ", "))
 		case FieldSelector:
 			return fmt.Sprintf("(%s).%s", glslExpr(&e.Exprs[0]), glslExpr(&e.Exprs[1]))
 		case Index:
@@ -256,7 +258,7 @@ func (p *Program) glslBlock(b *Block, level int, localVarIndex int) []string {
 			}
 			var op string
 			switch s.ForOp {
-			case LessThan, LessEqual, GreaterThan, GreaterEqual, Equal, NotEqual:
+			case LessThanOp, LessThanEqualOp, GreaterThanOp, GreaterThanEqualOp, EqualOp, NotEqualOp:
 				op = string(s.ForOp)
 			default:
 				op = fmt.Sprintf("?(unexpected op: %s)", string(s.ForOp))
diff --git a/internal/shaderir/ir_test.go b/internal/shaderir/ir_test.go
index 9eb7e6d21..a479b59a1 100644
--- a/internal/shaderir/ir_test.go
+++ b/internal/shaderir/ir_test.go
@@ -91,6 +91,13 @@ func varNameExpr(vt VariableType, index int) Expr {
 	}
 }
 
+func builtinFuncExpr(f BuiltinFunc) Expr {
+	return Expr{
+		Type:        BuiltinFuncExpr,
+		BuiltinFunc: f,
+	}
+}
+
 func identExpr(ident string) Expr {
 	return Expr{
 		Type:  Ident,
@@ -113,11 +120,10 @@ func selectionExpr(cond, a, b Expr) Expr {
 	}
 }
 
-func callExpr(name string, args ...Expr) Expr {
+func callExpr(callee Expr, args ...Expr) Expr {
 	return Expr{
 		Type:  Call,
-		Ident: name,
-		Exprs: args,
+		Exprs: append([]Expr{callee}, args...),
 	}
 }
 
@@ -388,13 +394,13 @@ varying vec3 V0;`,
 							nil,
 							exprStmt(
 								callExpr(
-									"F1",
+									identExpr("F1"),
 								),
 							),
 							assignStmt(
 								varNameExpr(Local, 2),
 								callExpr(
-									"F2",
+									identExpr("F2"),
 									varNameExpr(Local, 0),
 									varNameExpr(Local, 1),
 								),
@@ -404,8 +410,39 @@ varying vec3 V0;`,
 				},
 			},
 			Glsl: `void F0(in float l0, in float l1, out vec2 l2) {
-	F1();
-	l2 = F2(l0, l1);
+	(F1)();
+	l2 = (F2)(l0, l1);
+}`,
+		},
+		{
+			Name: "BuiltinFunc",
+			Program: Program{
+				Funcs: []Func{
+					{
+						Name: "F0",
+						InParams: []Type{
+							{Main: Float},
+							{Main: Float},
+						},
+						OutParams: []Type{
+							{Main: Float},
+						},
+						Block: block(
+							nil,
+							assignStmt(
+								varNameExpr(Local, 2),
+								callExpr(
+									builtinFuncExpr(Min),
+									varNameExpr(Local, 0),
+									varNameExpr(Local, 1),
+								),
+							),
+						),
+					},
+				},
+			},
+			Glsl: `void F0(in float l0, in float l1, out float l2) {
+	l2 = (min)(l0, l1);
 }`,
 		},
 		{
@@ -454,7 +491,7 @@ varying vec3 V0;`,
 							nil,
 							ifStmt(
 								binaryExpr(
-									Equal,
+									EqualOp,
 									varNameExpr(Local, 0),
 									floatExpr(0),
 								),
@@ -503,7 +540,7 @@ varying vec3 V0;`,
 							forStmt(
 								0,
 								100,
-								LessThan,
+								LessThanOp,
 								1,
 								block(
 									nil,
diff --git a/internal/shaderir/program.go b/internal/shaderir/program.go
index 2befe1d4e..f85d5523c 100644
--- a/internal/shaderir/program.go
+++ b/internal/shaderir/program.go
@@ -83,13 +83,14 @@ const (
 )
 
 type Expr struct {
-	Type     ExprType
-	Exprs    []Expr
-	Variable Variable
-	Int      int32
-	Float    float32
-	Ident    string
-	Op       Op
+	Type        ExprType
+	Exprs       []Expr
+	Variable    Variable
+	Int         int32
+	Float       float32
+	BuiltinFunc BuiltinFunc
+	Ident       string
+	Op          Op
 }
 
 type ExprType int
@@ -98,6 +99,7 @@ const (
 	IntExpr ExprType = iota
 	FloatExpr
 	VarName
+	BuiltinFuncExpr
 	Ident
 	Unary
 	Binary
@@ -122,23 +124,75 @@ const (
 type Op string
 
 const (
-	Add          Op = "+"
-	Sub          Op = "-"
-	Neg          Op = "!"
-	Mul          Op = "*"
-	Div          Op = "/"
-	Mod          Op = "%"
-	LeftShift    Op = "<<"
-	RightShift   Op = ">>"
-	LessThan     Op = "<"
-	LessEqual    Op = "<="
-	GreaterThan  Op = ">"
-	GreaterEqual Op = ">="
-	Equal        Op = "=="
-	NotEqual     Op = "!="
-	And          Op = "&"
-	Xor          Op = "^"
-	Or           Op = "|"
-	AndAnd       Op = "&&"
-	OrOr         Op = "||"
+	Add                Op = "+"
+	Sub                Op = "-"
+	Neg                Op = "!"
+	Mul                Op = "*"
+	Div                Op = "/"
+	ModOp              Op = "%"
+	LeftShift          Op = "<<"
+	RightShift         Op = ">>"
+	LessThanOp         Op = "<"
+	LessThanEqualOp    Op = "<="
+	GreaterThanOp      Op = ">"
+	GreaterThanEqualOp Op = ">="
+	EqualOp            Op = "=="
+	NotEqualOp         Op = "!="
+	And                Op = "&"
+	Xor                Op = "^"
+	Or                 Op = "|"
+	AndAnd             Op = "&&"
+	OrOr               Op = "||"
+)
+
+type BuiltinFunc string
+
+const (
+	Radians          BuiltinFunc = "radians"
+	Degrees          BuiltinFunc = "degrees"
+	Sin              BuiltinFunc = "sin"
+	Cos              BuiltinFunc = "cos"
+	Tan              BuiltinFunc = "tan"
+	Asin             BuiltinFunc = "asin"
+	Acos             BuiltinFunc = "acos"
+	Atan             BuiltinFunc = "atan"
+	Pow              BuiltinFunc = "pow"
+	Exp              BuiltinFunc = "exp"
+	Log              BuiltinFunc = "log"
+	Exp2             BuiltinFunc = "exp2"
+	Log2             BuiltinFunc = "log2"
+	Sqrt             BuiltinFunc = "sqrt"
+	Inversesqrt      BuiltinFunc = "inversesqrt"
+	Abs              BuiltinFunc = "abs"
+	Sign             BuiltinFunc = "sign"
+	Floor            BuiltinFunc = "floor"
+	Ceil             BuiltinFunc = "ceil"
+	Fract            BuiltinFunc = "fract"
+	Mod              BuiltinFunc = "mod"
+	Min              BuiltinFunc = "min"
+	Max              BuiltinFunc = "max"
+	Clamp            BuiltinFunc = "clamp"
+	Mix              BuiltinFunc = "mix"
+	Step             BuiltinFunc = "step"
+	Smoothstep       BuiltinFunc = "smoothstep"
+	Length           BuiltinFunc = "length"
+	Distance         BuiltinFunc = "distance"
+	Dot              BuiltinFunc = "dot"
+	Cross            BuiltinFunc = "cross"
+	Normalize        BuiltinFunc = "normalize"
+	Faceforward      BuiltinFunc = "faceforward"
+	Reflect          BuiltinFunc = "reflect"
+	MatrixCompMult   BuiltinFunc = "matrixCompMult"
+	OuterProduct     BuiltinFunc = "outerProduct"
+	Transpose        BuiltinFunc = "transpose"
+	LessThan         BuiltinFunc = "lessThan"
+	LessThanEqual    BuiltinFunc = "lessThanEqual"
+	GreaterThan      BuiltinFunc = "greaterThan"
+	GreaterThanEqual BuiltinFunc = "greaterThanEqual"
+	Equal            BuiltinFunc = "equal"
+	NotEqual         BuiltinFunc = "notEqual"
+	Any              BuiltinFunc = "any"
+	All              BuiltinFunc = "all"
+	Not              BuiltinFunc = "not"
+	Texture2D        BuiltinFunc = "texture2D"
 )