builtins

Documentation

Overview

Package builtins contains the definitions of all OpenGL ES Shading Language builtin functions.

It is not expected to be used directly by the user, it just provides the other packages with the list of builtin functions, their signatures and implementations.

Index

• Variables

Variables

var BuiltinFunctions = []ast.BuiltinFunction{

	{
		RetType: &ast.BuiltinType{Precision: ast.HighP, Type: ast.TUint},
		SymName: "packSnorm2x16",
		Params:  makeParams([]ast.Type{&ast.BuiltinType{Type: ast.TVec2}}),
		Impl: func(v []ast.Value) ast.Value {
			vec := v[0].(ast.VectorValue)
			x, y := toFloat(vec.Members[0]), toFloat(vec.Members[1])
			x = round(math.Min(math.Max(x, -1.0), 1.0) * factorSPack)
			y = round(math.Min(math.Max(y, -1.0), 1.0) * factorSPack)
			return ast.UintValue(int16(x)) + ast.UintValue(int16(y))<<16
		},
	},
	{
		RetType: &ast.BuiltinType{Precision: ast.HighP, Type: ast.TUint},
		SymName: "packUnorm2x16",
		Params:  makeParams([]ast.Type{&ast.BuiltinType{Type: ast.TVec2}}),
		Impl: func(v []ast.Value) ast.Value {
			vec := v[0].(ast.VectorValue)
			x, y := toFloat(vec.Members[0]), toFloat(vec.Members[1])
			x = round(math.Min(math.Max(x, 0.0), 1.0) * factorUPack)
			y = round(math.Min(math.Max(y, 0.0), 1.0) * factorUPack)
			return ast.UintValue(uint16(x)) + ast.UintValue(uint16(y))<<16
		},
	},
	{
		RetType: &ast.BuiltinType{Precision: ast.HighP, Type: ast.TVec2},
		SymName: "unpackSnorm2x16",
		Params:  makeParams([]ast.Type{&ast.BuiltinType{Precision: ast.HighP, Type: ast.TUint}}),
		Impl: func(v []ast.Value) ast.Value {
			pack := toUint(v[0])
			vec := []int16{int16(pack), int16(pack >> 16)}
			return makeFloatVector(2, func(i uint8) ast.Value {
				return ast.FloatValue(math.Min(
					math.Max(float64(vec[i])/factorSPack, -1.0), 1.0))
			})
		},
	},
	{
		RetType: &ast.BuiltinType{Precision: ast.HighP, Type: ast.TVec2},
		SymName: "unpackUnorm2x16",
		Params:  makeParams([]ast.Type{&ast.BuiltinType{Precision: ast.HighP, Type: ast.TUint}}),
		Impl: func(v []ast.Value) ast.Value {
			pack := toUint(v[0])
			vec := []uint16{uint16(pack), uint16(pack >> 16)}
			return makeFloatVector(2, func(i uint8) ast.Value {
				return ast.FloatValue(math.Min(
					math.Max(float64(vec[i])/factorUPack, -1.0), 1.0))
			})
		},
	},
	{
		RetType: &ast.BuiltinType{Precision: ast.HighP, Type: ast.TUint},
		SymName: "packHalf2x16",
		Params:  makeParams([]ast.Type{&ast.BuiltinType{Precision: ast.MediumP, Type: ast.TVec2}}),
		Impl: func(v []ast.Value) ast.Value {
			vec := v[0].(ast.VectorValue)
			x := f16.From(float32(toFloat(vec.Members[0])))
			y := f16.From(float32(toFloat(vec.Members[1])))
			return ast.UintValue(x) + ast.UintValue(y)<<16
		},
	},
	{
		RetType: &ast.BuiltinType{Precision: ast.MediumP, Type: ast.TVec2},
		SymName: "unpackHalf2x16",
		Params:  makeParams([]ast.Type{&ast.BuiltinType{Precision: ast.HighP, Type: ast.TUint}}),
		Impl: func(v []ast.Value) ast.Value {
			pack := toUint(v[0])
			vec := []f16.Number{f16.Number(pack), f16.Number(pack >> 16)}
			return makeFloatVector(2,
				func(i uint8) ast.Value { return ast.FloatValue(vec[i].Float32()) })
		},
	},

	{
		RetType: &ast.BuiltinType{Type: ast.TVec3},
		SymName: "cross",
		Params: makeParams([]ast.Type{&ast.BuiltinType{Type: ast.TVec3},
			&ast.BuiltinType{Type: ast.TVec3}}),

		Impl: func(v []ast.Value) ast.Value {
			x, y := v[0].(ast.VectorValue).Members, v[1].(ast.VectorValue).Members

			return ast.NewVectorValue(ast.TVec3, func(i uint8) ast.Value {
				j, k := (i+1)%3, (i+2)%3
				return x[j].(ast.FloatValue)*y[k].(ast.FloatValue) -
					y[j].(ast.FloatValue)*x[k].(ast.FloatValue)
			})
		},
	},
}

BuiltinFunctions contains the list of builtin functions defined by the package, in no particular order.

PS: The list showed by godoc is not complete. More functions are added during package init(). For a definitive list, see The OpenGL ES Shading Language specification, section 8.