ebiten/internal/shader/expr.go

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// Copyright 2020 The Ebiten Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package shader
import (
"fmt"
"go/ast"
gconstant "go/constant"
"go/token"
"regexp"
"strconv"
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"github.com/hajimehoshi/ebiten/internal/shaderir"
)
func canTruncateToInteger(v gconstant.Value) bool {
return gconstant.ToInt(v).Kind() != gconstant.Unknown
}
var textureVariableRe = regexp.MustCompile(`\A__t(\d+)\z`)
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func (cs *compileState) parseExpr(block *block, expr ast.Expr) ([]shaderir.Expr, []shaderir.Type, []shaderir.Stmt, bool) {
switch e := expr.(type) {
case *ast.BasicLit:
switch e.Kind {
case token.INT:
return []shaderir.Expr{
{
Type: shaderir.NumberExpr,
Const: gconstant.MakeFromLiteral(e.Value, e.Kind, 0),
},
}, []shaderir.Type{{Main: shaderir.Int}}, nil, true
case token.FLOAT:
return []shaderir.Expr{
{
Type: shaderir.NumberExpr,
Const: gconstant.MakeFromLiteral(e.Value, e.Kind, 0),
},
}, []shaderir.Type{{Main: shaderir.Float}}, nil, true
default:
cs.addError(e.Pos(), fmt.Sprintf("literal not implemented: %#v", e))
}
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case *ast.BinaryExpr:
var stmts []shaderir.Stmt
// Prase LHS first for the order of the statements.
lhs, ts, ss, ok := cs.parseExpr(block, e.X)
if !ok {
return nil, nil, nil, false
}
if len(lhs) != 1 {
cs.addError(e.Pos(), fmt.Sprintf("multiple-value context is not available at a binary operator: %s", e.X))
return nil, nil, nil, false
}
stmts = append(stmts, ss...)
lhst := ts[0]
rhs, ts, ss, ok := cs.parseExpr(block, e.Y)
if !ok {
return nil, nil, nil, false
}
if len(rhs) != 1 {
cs.addError(e.Pos(), fmt.Sprintf("multiple-value context is not available at a binary operator: %s", e.Y))
return nil, nil, nil, false
}
stmts = append(stmts, ss...)
rhst := ts[0]
if lhs[0].Type == shaderir.NumberExpr && rhs[0].Type == shaderir.NumberExpr {
op := e.Op
// https://golang.org/pkg/go/constant/#BinaryOp
// "To force integer division of Int operands, use op == token.QUO_ASSIGN instead of
// token.QUO; the result is guaranteed to be Int in this case."
if op == token.QUO && lhs[0].Const.Kind() == gconstant.Int && rhs[0].Const.Kind() == gconstant.Int {
op = token.QUO_ASSIGN
}
var v gconstant.Value
var t shaderir.Type
switch op {
case token.EQL, token.NEQ, token.LSS, token.LEQ, token.GTR, token.GEQ:
v = gconstant.MakeBool(gconstant.Compare(lhs[0].Const, op, rhs[0].Const))
t = shaderir.Type{Main: shaderir.Bool}
default:
v = gconstant.BinaryOp(lhs[0].Const, op, rhs[0].Const)
if v.Kind() == gconstant.Float {
t = shaderir.Type{Main: shaderir.Float}
} else {
t = shaderir.Type{Main: shaderir.Int}
}
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}
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return []shaderir.Expr{
{
Type: shaderir.NumberExpr,
Const: v,
},
}, []shaderir.Type{t}, stmts, true
}
op, ok := shaderir.OpFromToken(e.Op)
if !ok {
cs.addError(e.Pos(), fmt.Sprintf("unexpected operator: %s", e.Op))
return nil, nil, nil, false
}
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var t shaderir.Type
switch {
case op == shaderir.LessThanOp || op == shaderir.LessThanEqualOp || op == shaderir.GreaterThanOp || op == shaderir.GreaterThanEqualOp || op == shaderir.EqualOp || op == shaderir.NotEqualOp || op == shaderir.AndAnd || op == shaderir.OrOr:
t = shaderir.Type{Main: shaderir.Bool}
case lhs[0].Type == shaderir.NumberExpr && rhs[0].Type != shaderir.NumberExpr:
if rhst.Main == shaderir.Int {
if !canTruncateToInteger(lhs[0].Const) {
cs.addError(e.Pos(), fmt.Sprintf("constant %s truncated to integer", lhs[0].Const.String()))
return nil, nil, nil, false
}
lhs[0].ConstType = shaderir.ConstTypeInt
}
t = rhst
case lhs[0].Type != shaderir.NumberExpr && rhs[0].Type == shaderir.NumberExpr:
if lhst.Main == shaderir.Int {
if !canTruncateToInteger(rhs[0].Const) {
cs.addError(e.Pos(), fmt.Sprintf("constant %s truncated to integer", rhs[0].Const.String()))
return nil, nil, nil, false
}
rhs[0].ConstType = shaderir.ConstTypeInt
}
t = lhst
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case lhst.Equal(&rhst):
t = lhst
case lhst.Main == shaderir.Float || lhst.Main == shaderir.Int:
switch rhst.Main {
case shaderir.Int:
t = lhst
case shaderir.Float, shaderir.Vec2, shaderir.Vec3, shaderir.Vec4, shaderir.Mat2, shaderir.Mat3, shaderir.Mat4:
t = rhst
default:
cs.addError(e.Pos(), fmt.Sprintf("types don't match: %s %s %s", lhst.String(), e.Op, rhst.String()))
return nil, nil, nil, false
}
case rhst.Main == shaderir.Float || rhst.Main == shaderir.Int:
switch lhst.Main {
case shaderir.Int:
t = rhst
case shaderir.Float, shaderir.Vec2, shaderir.Vec3, shaderir.Vec4, shaderir.Mat2, shaderir.Mat3, shaderir.Mat4:
t = lhst
default:
cs.addError(e.Pos(), fmt.Sprintf("types don't match: %s %s %s", lhst.String(), e.Op, rhst.String()))
return nil, nil, nil, false
}
case lhst.Main == shaderir.Vec2 && rhst.Main == shaderir.Mat2 ||
lhst.Main == shaderir.Mat2 && rhst.Main == shaderir.Vec2:
t = shaderir.Type{Main: shaderir.Vec2}
case lhst.Main == shaderir.Vec3 && rhst.Main == shaderir.Mat3 ||
lhst.Main == shaderir.Mat3 && rhst.Main == shaderir.Vec3:
t = shaderir.Type{Main: shaderir.Vec3}
case lhst.Main == shaderir.Vec4 && rhst.Main == shaderir.Mat4 ||
lhst.Main == shaderir.Mat4 && rhst.Main == shaderir.Vec4:
t = shaderir.Type{Main: shaderir.Vec4}
default:
cs.addError(e.Pos(), fmt.Sprintf("invalid expression: %s %s %s", lhst.String(), e.Op, rhst.String()))
return nil, nil, nil, false
}
return []shaderir.Expr{
{
Type: shaderir.Binary,
Op: op,
Exprs: []shaderir.Expr{lhs[0], rhs[0]},
},
}, []shaderir.Type{t}, stmts, true
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case *ast.CallExpr:
var (
callee shaderir.Expr
args []shaderir.Expr
argts []shaderir.Type
stmts []shaderir.Stmt
)
// Parse the argument first for the order of the statements.
for _, a := range e.Args {
es, ts, ss, ok := cs.parseExpr(block, a)
if !ok {
return nil, nil, nil, false
}
if len(es) > 1 && len(e.Args) > 1 {
cs.addError(e.Pos(), fmt.Sprintf("single-value context and multiple-value context cannot be mixed: %s", e.Fun))
return nil, nil, nil, false
}
args = append(args, es...)
argts = append(argts, ts...)
stmts = append(stmts, ss...)
}
// TODO: When len(ss) is not 0?
es, _, ss, ok := cs.parseExpr(block, e.Fun)
if !ok {
return nil, nil, nil, false
}
if len(es) != 1 {
cs.addError(e.Pos(), fmt.Sprintf("multiple-value context is not available at a callee: %s", e.Fun))
return nil, nil, nil, false
}
callee = es[0]
stmts = append(stmts, ss...)
// For built-in functions, we can call this in this position. Return an expression for the function
// call.
if callee.Type == shaderir.BuiltinFuncExpr {
if callee.BuiltinFunc == shaderir.Len {
if len(args) != 1 {
cs.addError(e.Pos(), fmt.Sprintf("number of len's arguments must be 1 but %d", len(args)))
return nil, nil, nil, false
}
if argts[0].Main != shaderir.Array {
cs.addError(e.Pos(), fmt.Sprintf("len takes an array but %s", argts[0].String()))
return nil, nil, nil, false
}
return []shaderir.Expr{
{
Type: shaderir.NumberExpr,
Const: gconstant.MakeInt64(int64(argts[0].Length)),
ConstType: shaderir.ConstTypeInt,
},
}, []shaderir.Type{{Main: shaderir.Int}}, stmts, true
}
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var t shaderir.Type
switch callee.BuiltinFunc {
case shaderir.BoolF:
t = shaderir.Type{Main: shaderir.Bool}
case shaderir.IntF:
t = shaderir.Type{Main: shaderir.Int}
case shaderir.FloatF:
t = shaderir.Type{Main: shaderir.Float}
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case shaderir.Vec2F:
t = shaderir.Type{Main: shaderir.Vec2}
case shaderir.Vec3F:
t = shaderir.Type{Main: shaderir.Vec3}
case shaderir.Vec4F:
t = shaderir.Type{Main: shaderir.Vec4}
case shaderir.Mat2F:
t = shaderir.Type{Main: shaderir.Mat2}
case shaderir.Mat3F:
t = shaderir.Type{Main: shaderir.Mat3}
case shaderir.Mat4F:
t = shaderir.Type{Main: shaderir.Mat4}
case shaderir.Step:
t = argts[1]
case shaderir.Smoothstep:
t = argts[2]
case shaderir.Length, shaderir.Distance, shaderir.Dot:
t = shaderir.Type{Main: shaderir.Float}
case shaderir.Cross:
t = shaderir.Type{Main: shaderir.Vec3}
case shaderir.Texture2DF:
t = shaderir.Type{Main: shaderir.Vec4}
default:
t = argts[0]
}
return []shaderir.Expr{
{
Type: shaderir.Call,
Exprs: append([]shaderir.Expr{callee}, args...),
},
}, []shaderir.Type{t}, stmts, true
}
if callee.Type != shaderir.FunctionExpr {
cs.addError(e.Pos(), fmt.Sprintf("function callee must be a funciton name but %s", e.Fun))
return nil, nil, nil, false
}
f := cs.funcs[callee.Index]
var outParams []int
for _, p := range f.ir.OutParams {
idx := block.totalLocalVariableNum()
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block.vars = append(block.vars, variable{
typ: p,
})
args = append(args, shaderir.Expr{
Type: shaderir.LocalVariable,
Index: idx,
})
outParams = append(outParams, idx)
}
if t := f.ir.Return; t.Main != shaderir.None {
if len(outParams) != 0 {
cs.addError(e.Pos(), fmt.Sprintf("a function returning value cannot have out-params so far: %s", e.Fun))
return nil, nil, nil, false
}
idx := block.totalLocalVariableNum()
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block.vars = append(block.vars, variable{
typ: t,
})
// Calling the function should be done eariler to treat out-params correctly.
stmts = append(stmts, shaderir.Stmt{
Type: shaderir.Assign,
Exprs: []shaderir.Expr{
{
Type: shaderir.LocalVariable,
Index: idx,
},
{
Type: shaderir.Call,
Exprs: append([]shaderir.Expr{callee}, args...),
},
},
})
// The actual expression here is just a local variable that includes the result of the
// function call.
return []shaderir.Expr{
{
Type: shaderir.LocalVariable,
Index: idx,
},
}, []shaderir.Type{t}, stmts, true
}
// Even if the function doesn't return anything, calling the function should be done eariler to keep
// the evaluation order.
stmts = append(stmts, shaderir.Stmt{
Type: shaderir.ExprStmt,
Exprs: []shaderir.Expr{
{
Type: shaderir.Call,
Exprs: append([]shaderir.Expr{callee}, args...),
},
},
})
if len(outParams) == 0 {
// TODO: Is this an error?
}
var exprs []shaderir.Expr
for _, p := range outParams {
exprs = append(exprs, shaderir.Expr{
Type: shaderir.LocalVariable,
Index: p,
})
}
return exprs, f.ir.OutParams, stmts, true
case *ast.Ident:
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if e.Name == "true" || e.Name == "false" {
return []shaderir.Expr{
{
Type: shaderir.NumberExpr,
Const: gconstant.MakeBool(e.Name == "true"),
},
}, []shaderir.Type{{Main: shaderir.Bool}}, nil, true
}
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if i, t, ok := block.findLocalVariable(e.Name); ok {
return []shaderir.Expr{
{
Type: shaderir.LocalVariable,
Index: i,
},
}, []shaderir.Type{t}, nil, true
}
if i, ok := cs.findFunction(e.Name); ok {
return []shaderir.Expr{
{
Type: shaderir.FunctionExpr,
Index: i,
},
}, nil, nil, true
}
if i, ok := cs.findUniformVariable(e.Name); ok {
return []shaderir.Expr{
{
Type: shaderir.UniformVariable,
Index: i,
},
}, []shaderir.Type{cs.ir.Uniforms[i]}, nil, true
}
if f, ok := shaderir.ParseBuiltinFunc(e.Name); ok {
return []shaderir.Expr{
{
Type: shaderir.BuiltinFuncExpr,
BuiltinFunc: f,
},
}, nil, nil, true
}
if m := textureVariableRe.FindStringSubmatch(e.Name); m != nil {
i, _ := strconv.Atoi(m[1])
return []shaderir.Expr{
{
Type: shaderir.TextureVariable,
Index: i,
},
}, nil, nil, true
}
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cs.addError(e.Pos(), fmt.Sprintf("unexpected identifier: %s", e.Name))
case *ast.ParenExpr:
return cs.parseExpr(block, e.X)
case *ast.SelectorExpr:
exprs, _, stmts, ok := cs.parseExpr(block, e.X)
if !ok {
return nil, nil, nil, false
}
if len(exprs) != 1 {
cs.addError(e.Pos(), fmt.Sprintf("multiple-value context is not available at a selector: %s", e.X))
return nil, nil, nil, false
}
var t shaderir.Type
switch len(e.Sel.Name) {
case 1:
t.Main = shaderir.Float
case 2:
t.Main = shaderir.Vec2
case 3:
t.Main = shaderir.Vec3
case 4:
t.Main = shaderir.Vec4
default:
cs.addError(e.Pos(), fmt.Sprintf("unexpected swizzling: %s", e.Sel.Name))
return nil, nil, nil, false
}
return []shaderir.Expr{
{
Type: shaderir.FieldSelector,
Exprs: []shaderir.Expr{
exprs[0],
{
Type: shaderir.SwizzlingExpr,
Swizzling: e.Sel.Name,
},
},
},
}, []shaderir.Type{t}, stmts, true
case *ast.UnaryExpr:
exprs, t, stmts, ok := cs.parseExpr(block, e.X)
if !ok {
return nil, nil, nil, false
}
if len(exprs) != 1 {
cs.addError(e.Pos(), fmt.Sprintf("multiple-value context is not available at a unary operator: %s", e.X))
return nil, nil, nil, false
}
if exprs[0].Type == shaderir.NumberExpr {
v := gconstant.UnaryOp(e.Op, exprs[0].Const, 0)
t := shaderir.Type{Main: shaderir.Int}
if v.Kind() == gconstant.Float {
t = shaderir.Type{Main: shaderir.Float}
}
return []shaderir.Expr{
{
Type: shaderir.NumberExpr,
Const: v,
},
}, []shaderir.Type{t}, stmts, true
}
var op shaderir.Op
switch e.Op {
case token.ADD:
op = shaderir.Add
case token.SUB:
op = shaderir.Sub
case token.NOT:
op = shaderir.NotOp
default:
cs.addError(e.Pos(), fmt.Sprintf("unexpected operator: %s", e.Op))
return nil, nil, nil, false
}
return []shaderir.Expr{
{
Type: shaderir.Unary,
Op: op,
Exprs: exprs,
},
}, t, stmts, true
case *ast.CompositeLit:
t, ok := cs.parseType(block, e.Type)
if !ok {
return nil, nil, nil, false
}
if t.Main == shaderir.Array && t.Length == -1 {
t.Length = len(e.Elts)
}
idx := block.totalLocalVariableNum()
block.vars = append(block.vars, variable{
typ: t,
})
var stmts []shaderir.Stmt
for i, e := range e.Elts {
exprs, _, ss, ok := cs.parseExpr(block, e)
if !ok {
return nil, nil, nil, false
}
if len(exprs) != 1 {
cs.addError(e.Pos(), fmt.Sprintf("multiple-value context is not available at a composite literal"))
return nil, nil, nil, false
}
stmts = append(stmts, ss...)
stmts = append(stmts, shaderir.Stmt{
Type: shaderir.Assign,
Exprs: []shaderir.Expr{
{
Type: shaderir.Index,
Exprs: []shaderir.Expr{
{
Type: shaderir.LocalVariable,
Index: idx,
},
{
Type: shaderir.NumberExpr,
Const: gconstant.MakeInt64(int64(i)),
ConstType: shaderir.ConstTypeInt,
},
},
},
exprs[0],
},
})
}
return []shaderir.Expr{
{
Type: shaderir.LocalVariable,
Index: idx,
},
}, []shaderir.Type{t}, stmts, true
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case *ast.IndexExpr:
var stmts []shaderir.Stmt
// Parse the index first
exprs, _, ss, ok := cs.parseExpr(block, e.Index)
if !ok {
return nil, nil, nil, false
}
stmts = append(stmts, ss...)
if len(exprs) != 1 {
cs.addError(e.Pos(), fmt.Sprintf("multiple-value context is not available at an index expression"))
return nil, nil, nil, false
}
idx := exprs[0]
if idx.Type == shaderir.NumberExpr {
if !canTruncateToInteger(idx.Const) {
cs.addError(e.Pos(), fmt.Sprintf("constant %s truncated to integer", idx.Const.String()))
return nil, nil, nil, false
}
idx.ConstType = shaderir.ConstTypeInt
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}
exprs, ts, ss, ok := cs.parseExpr(block, e.X)
if !ok {
return nil, nil, nil, false
}
stmts = append(stmts, ss...)
if len(exprs) != 1 {
cs.addError(e.Pos(), fmt.Sprintf("multiple-value context is not available at an index expression"))
return nil, nil, nil, false
}
x := exprs[0]
t := ts[0]
var typ shaderir.Type
switch t.Main {
case shaderir.Vec2, shaderir.Vec3, shaderir.Vec4:
typ = shaderir.Type{Main: shaderir.Float}
case shaderir.Mat2:
typ = shaderir.Type{Main: shaderir.Vec2}
case shaderir.Mat3:
typ = shaderir.Type{Main: shaderir.Vec3}
case shaderir.Mat4:
typ = shaderir.Type{Main: shaderir.Vec4}
case shaderir.Array:
typ = t.Sub[0]
default:
cs.addError(e.Pos(), fmt.Sprintf("index operator cannot be applied to the type %s", t.String()))
return nil, nil, nil, false
}
return []shaderir.Expr{
{
Type: shaderir.Index,
Exprs: []shaderir.Expr{
x,
idx,
},
},
}, []shaderir.Type{typ}, stmts, true
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default:
cs.addError(e.Pos(), fmt.Sprintf("expression not implemented: %#v", e))
}
return nil, nil, nil, false
}