ebiten/internal/shader/shader.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 (
"bufio"
"bytes"
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"fmt"
"go/ast"
gconstant "go/constant"
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"go/parser"
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"go/token"
"regexp"
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"strings"
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"github.com/hajimehoshi/ebiten/v2/internal/shaderir"
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)
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type variable struct {
name string
typ shaderir.Type
forLoopCounter bool
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}
type constant struct {
name string
typ shaderir.Type
value gconstant.Value
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}
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type function struct {
name string
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ir shaderir.Func
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}
type compileState struct {
fs *token.FileSet
vertexEntry string
fragmentEntry string
unit shaderir.Unit
ir shaderir.Program
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funcs []function
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global block
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varyingParsed bool
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errs []string
}
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func (cs *compileState) findFunction(name string) (int, bool) {
for i, f := range cs.funcs {
if f.name == name {
return i, true
}
}
return 0, false
}
func (cs *compileState) findUniformVariable(name string) (int, bool) {
for i, u := range cs.ir.UniformNames {
if u == name {
return i, true
}
}
return 0, false
}
type typ struct {
name string
ir shaderir.Type
}
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type block struct {
types []typ
vars []variable
unusedVars map[int]token.Pos
consts []constant
pos token.Pos
outer *block
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ir *shaderir.Block
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}
func (b *block) totalLocalVariableCount() int {
c := len(b.vars)
if b.outer != nil {
c += b.outer.totalLocalVariableCount()
}
return c
}
func (b *block) addNamedLocalVariable(name string, typ shaderir.Type, pos token.Pos) {
b.vars = append(b.vars, variable{
name: name,
typ: typ,
})
if name == "_" {
return
}
idx := len(b.vars) - 1
if b.unusedVars == nil {
b.unusedVars = map[int]token.Pos{}
}
b.unusedVars[idx] = pos
}
func (b *block) findLocalVariable(name string, markLocalVariableUsed bool) (int, shaderir.Type, bool) {
if name == "" || name == "_" {
panic("shader: variable name must be non-empty and non-underscore")
}
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idx := 0
for outer := b.outer; outer != nil; outer = outer.outer {
idx += len(outer.vars)
}
for i, v := range b.vars {
if v.name == name {
if markLocalVariableUsed {
delete(b.unusedVars, i)
}
return idx + i, v.typ, true
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}
}
if b.outer != nil {
return b.outer.findLocalVariable(name, markLocalVariableUsed)
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}
return 0, shaderir.Type{}, false
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}
func (b *block) findLocalVariableByIndex(idx int) (shaderir.Type, bool) {
bs := []*block{b}
for outer := b.outer; outer != nil; outer = outer.outer {
bs = append(bs, outer)
}
for i := len(bs) - 1; i >= 0; i-- {
if len(bs[i].vars) <= idx {
idx -= len(bs[i].vars)
continue
}
return bs[i].vars[idx].typ, true
}
return shaderir.Type{}, false
}
func (b *block) findConstant(name string) (constant, bool) {
if name == "" || name == "_" {
panic("shader: constant name must be non-empty and non-underscore")
}
for _, c := range b.consts {
if c.name == name {
return c, true
}
}
if b.outer != nil {
return b.outer.findConstant(name)
}
return constant{}, false
}
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type ParseError struct {
errs []string
}
func (p *ParseError) Error() string {
return strings.Join(p.errs, "\n")
}
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func Compile(src []byte, vertexEntry, fragmentEntry string, textureCount int) (*shaderir.Program, error) {
unit, err := ParseCompilerDirectives(src)
if err != nil {
return nil, err
}
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fs := token.NewFileSet()
f, err := parser.ParseFile(fs, "", src, parser.AllErrors)
if err != nil {
return nil, err
}
s := &compileState{
fs: fs,
vertexEntry: vertexEntry,
fragmentEntry: fragmentEntry,
unit: unit,
}
s.ir.SourceHash = shaderir.CalcSourceHash(src)
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s.global.ir = &shaderir.Block{}
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s.parse(f)
if len(s.errs) > 0 {
return nil, &ParseError{s.errs}
}
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// TODO: Resolve identifiers?
// TODO: Resolve constants
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// TODO: Make a call graph and reorder the elements.
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s.ir.TextureCount = textureCount
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return &s.ir, nil
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}
func ParseCompilerDirectives(src []byte) (shaderir.Unit, error) {
// TODO: Change the unit to pixels in v3 (#2645).
unit := shaderir.Texels
// Go's whitespace is U+0020 (SP), U+0009 (\t), U+000d (\r), and U+000A (\n).
// See https://go.dev/ref/spec#Tokens
reUnit := regexp.MustCompile(`^[ \t\r\n]*//kage:unit\s+([^ \t\r\n]+)[ \t\r\n]*$`)
var unitParsed bool
buf := bytes.NewBuffer(src)
s := bufio.NewScanner(buf)
for s.Scan() {
m := reUnit.FindStringSubmatch(s.Text())
if m == nil {
continue
}
if unitParsed {
return 0, fmt.Errorf("shader: at most one //kage:unit can exist in a shader")
}
switch m[1] {
case "pixels":
unit = shaderir.Pixels
case "texels":
unit = shaderir.Texels
default:
return 0, fmt.Errorf("shader: invalid value for //kage:unit: %s", m[1])
}
unitParsed = true
}
return unit, nil
}
func (s *compileState) addError(pos token.Pos, str string) {
p := s.fs.Position(pos)
s.errs = append(s.errs, fmt.Sprintf("%s: %s", p, str))
}
func (cs *compileState) parse(f *ast.File) {
cs.ir.Unit = cs.unit
// Parse GenDecl for global variables, and then parse functions.
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for _, d := range f.Decls {
if _, ok := d.(*ast.FuncDecl); !ok {
ss, ok := cs.parseDecl(&cs.global, "", d)
if !ok {
return
}
cs.global.ir.Stmts = append(cs.global.ir.Stmts, ss...)
}
}
// Sort the uniform variable so that special variable starting with __ should come first.
var unames []string
var utypes []shaderir.Type
for i, u := range cs.ir.UniformNames {
if strings.HasPrefix(u, "__") {
unames = append(unames, u)
utypes = append(utypes, cs.ir.Uniforms[i])
}
}
// TODO: Check len(unames) == graphics.PreservedUniformVariablesNum. Unfortunately this is not true on tests.
for i, u := range cs.ir.UniformNames {
if !strings.HasPrefix(u, "__") {
unames = append(unames, u)
utypes = append(utypes, cs.ir.Uniforms[i])
}
}
cs.ir.UniformNames = unames
cs.ir.Uniforms = utypes
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// Parse function names so that any other function call the others.
// The function data is provisional and will be updated soon.
for _, d := range f.Decls {
fd, ok := d.(*ast.FuncDecl)
if !ok {
continue
}
n := fd.Name.Name
if n == cs.vertexEntry {
continue
}
if n == cs.fragmentEntry {
continue
}
for _, f := range cs.funcs {
if f.name == n {
cs.addError(d.Pos(), fmt.Sprintf("redeclared function: %s", n))
return
}
}
inParams, outParams, ret := cs.parseFuncParams(&cs.global, n, fd)
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var inT, outT []shaderir.Type
for _, v := range inParams {
inT = append(inT, v.typ)
}
for _, v := range outParams {
outT = append(outT, v.typ)
}
cs.funcs = append(cs.funcs, function{
name: n,
ir: shaderir.Func{
Index: len(cs.funcs),
InParams: inT,
OutParams: outT,
Return: ret,
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Block: &shaderir.Block{},
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},
})
}
// Parse functions.
for _, d := range f.Decls {
if f, ok := d.(*ast.FuncDecl); ok {
ss, ok := cs.parseDecl(&cs.global, f.Name.Name, d)
if !ok {
return
}
cs.global.ir.Stmts = append(cs.global.ir.Stmts, ss...)
}
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}
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if len(cs.errs) > 0 {
return
}
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for _, f := range cs.funcs {
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cs.ir.Funcs = append(cs.ir.Funcs, f.ir)
}
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}
func (cs *compileState) parseDecl(b *block, fname string, d ast.Decl) ([]shaderir.Stmt, bool) {
var stmts []shaderir.Stmt
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switch d := d.(type) {
case *ast.GenDecl:
switch d.Tok {
case token.TYPE:
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// TODO: Parse other types
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for _, s := range d.Specs {
s := s.(*ast.TypeSpec)
t, ok := cs.parseType(b, fname, s.Type)
if !ok {
return nil, false
}
n := s.Name.Name
for _, t := range b.types {
if t.name == n {
cs.addError(s.Pos(), fmt.Sprintf("%s redeclared in this block", n))
return nil, false
}
}
b.types = append(b.types, typ{
name: n,
ir: t,
})
}
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case token.CONST:
for _, s := range d.Specs {
s := s.(*ast.ValueSpec)
cs, ok := cs.parseConstant(b, fname, s)
if !ok {
return nil, false
}
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b.consts = append(b.consts, cs...)
}
case token.VAR:
for _, s := range d.Specs {
s := s.(*ast.ValueSpec)
vs, inits, ss, ok := cs.parseVariable(b, fname, s)
if !ok {
return nil, false
}
stmts = append(stmts, ss...)
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if b == &cs.global {
if len(inits) > 0 {
cs.addError(s.Pos(), "a uniform variable cannot have initial values")
return nil, false
}
// TODO: Should rhs be ignored?
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for i, v := range vs {
if !strings.HasPrefix(v.name, "__") {
if v.name[0] < 'A' || 'Z' < v.name[0] {
cs.addError(s.Names[i].Pos(), fmt.Sprintf("global variables must be exposed: %s", v.name))
}
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}
for _, name := range cs.ir.UniformNames {
if name == v.name {
cs.addError(s.Pos(), fmt.Sprintf("%s redeclared in this block", name))
return nil, false
}
}
cs.ir.UniformNames = append(cs.ir.UniformNames, v.name)
cs.ir.Uniforms = append(cs.ir.Uniforms, v.typ)
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}
continue
}
// base must be obtained before adding the variables.
base := b.totalLocalVariableCount()
for _, v := range vs {
b.addNamedLocalVariable(v.name, v.typ, d.Pos())
}
if len(inits) > 0 {
for i := range vs {
stmts = append(stmts, shaderir.Stmt{
Type: shaderir.Assign,
Exprs: []shaderir.Expr{
{
Type: shaderir.LocalVariable,
Index: base + i,
},
inits[i],
},
})
}
}
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}
case token.IMPORT:
cs.addError(d.Pos(), "import is forbidden")
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default:
cs.addError(d.Pos(), "unexpected token")
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}
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case *ast.FuncDecl:
f, ok := cs.parseFunc(b, d)
if !ok {
return nil, false
}
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if b != &cs.global {
cs.addError(d.Pos(), "non-global function is not implemented")
return nil, false
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}
switch d.Name.Name {
case cs.vertexEntry:
cs.ir.VertexFunc.Block = f.ir.Block
case cs.fragmentEntry:
cs.ir.FragmentFunc.Block = f.ir.Block
default:
// The function is already registered for their names.
for i := range cs.funcs {
if cs.funcs[i].name == d.Name.Name {
// Index is already determined by the provisional parsing.
f.ir.Index = cs.funcs[i].ir.Index
cs.funcs[i] = f
break
}
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}
}
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default:
cs.addError(d.Pos(), "unexpected decl")
return nil, false
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}
return stmts, true
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}
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// functionReturnTypes returns the original returning value types, if the given expression is call.
//
// Note that parseExpr returns the returning types for IR, not the original function.
func (cs *compileState) functionReturnTypes(block *block, expr ast.Expr) ([]shaderir.Type, bool) {
call, ok := expr.(*ast.CallExpr)
if !ok {
return nil, false
}
ident, ok := call.Fun.(*ast.Ident)
if !ok {
return nil, false
}
for _, f := range cs.funcs {
if f.name == ident.Name {
// TODO: Is it correct to combine out-params and return param?
ts := f.ir.OutParams
if f.ir.Return.Main != shaderir.None {
ts = append(ts, f.ir.Return)
}
return ts, true
}
}
return nil, false
}
func (s *compileState) parseVariable(block *block, fname string, vs *ast.ValueSpec) ([]variable, []shaderir.Expr, []shaderir.Stmt, bool) {
if len(vs.Names) != len(vs.Values) && len(vs.Values) != 1 && len(vs.Values) != 0 {
s.addError(vs.Pos(), "the numbers of lhs and rhs don't match")
return nil, nil, nil, false
}
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var declt shaderir.Type
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if vs.Type != nil {
var ok bool
declt, ok = s.parseType(block, fname, vs.Type)
if !ok {
return nil, nil, nil, false
}
}
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var (
vars []variable
inits []shaderir.Expr
stmts []shaderir.Stmt
)
// These variables are used only in multiple-value context.
var inittypes []shaderir.Type
var initexprs []shaderir.Expr
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for i, n := range vs.Names {
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t := declt
switch {
case len(vs.Values) == 0:
// No initialization
case len(vs.Names) == len(vs.Values):
// Single-value context
init := vs.Values[i]
es, rts, ss, ok := s.parseExpr(block, fname, init, true)
if !ok {
return nil, nil, nil, false
}
if t.Main == shaderir.None {
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ts, ok := s.functionReturnTypes(block, init)
if !ok {
ts = rts
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}
if len(ts) > 1 {
s.addError(vs.Pos(), "the numbers of lhs and rhs don't match")
}
t = ts[0]
if t.Main == shaderir.None {
t = toDefaultType(es[0].Const)
}
}
for i, rt := range rts {
if !canAssign(&t, &rt, es[i].Const) {
s.addError(vs.Pos(), fmt.Sprintf("cannot use type %s as type %s in variable declaration", rt.String(), t.String()))
}
}
inits = append(inits, es...)
stmts = append(stmts, ss...)
default:
// Multiple-value context
// See testcase/var_multiple.go for an actual case.
if i == 0 {
init := vs.Values[0]
var ss []shaderir.Stmt
var ok bool
initexprs, inittypes, ss, ok = s.parseExpr(block, fname, init, true)
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if !ok {
return nil, nil, nil, false
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}
stmts = append(stmts, ss...)
if t.Main == shaderir.None {
ts, ok := s.functionReturnTypes(block, init)
if ok {
inittypes = ts
}
if len(ts) != len(vs.Names) {
s.addError(vs.Pos(), "the numbers of lhs and rhs don't match")
continue
}
}
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}
if t.Main == shaderir.None && len(inittypes) > 0 {
t = inittypes[i]
// TODO: Is it possible to reach this?
if t.Main == shaderir.None {
t = toDefaultType(initexprs[i].Const)
}
}
if !canAssign(&t, &inittypes[i], initexprs[i].Const) {
s.addError(vs.Pos(), fmt.Sprintf("cannot use type %s as type %s in variable declaration", inittypes[i].String(), t.String()))
}
// Add the same initexprs for each variable.
inits = append(inits, initexprs...)
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}
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name := n.Name
for _, v := range append(block.vars, vars...) {
if v.name == name {
s.addError(vs.Pos(), fmt.Sprintf("duplicated local variable name: %s", name))
return nil, nil, nil, false
}
}
for _, c := range block.consts {
if c.name == name {
s.addError(vs.Pos(), fmt.Sprintf("duplicated local constant/variable name: %s", name))
return nil, nil, nil, false
}
}
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vars = append(vars, variable{
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name: name,
typ: t,
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})
}
return vars, inits, stmts, true
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}
func (s *compileState) parseConstant(block *block, fname string, vs *ast.ValueSpec) ([]constant, bool) {
var t shaderir.Type
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if vs.Type != nil {
var ok bool
t, ok = s.parseType(block, fname, vs.Type)
if !ok {
return nil, false
}
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}
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var cs []constant
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for i, n := range vs.Names {
name := n.Name
for _, c := range block.consts {
if c.name == name {
s.addError(vs.Pos(), fmt.Sprintf("duplicated local constant name: %s", name))
return nil, false
}
}
for _, v := range block.vars {
if v.name == name {
s.addError(vs.Pos(), fmt.Sprintf("duplicated local constant/variable name: %s", name))
return nil, false
}
}
es, ts, ss, ok := s.parseExpr(block, fname, vs.Values[i], false)
if !ok {
return nil, false
}
if len(ss) > 0 {
s.addError(vs.Pos(), fmt.Sprintf("invalid constant expression: %s", name))
return nil, false
}
if len(ts) != 1 || len(es) != 1 {
s.addError(vs.Pos(), fmt.Sprintf("invalid constant expression: %s", n))
return nil, false
}
if es[0].Type != shaderir.NumberExpr {
s.addError(vs.Pos(), fmt.Sprintf("constant expression must be a number but not: %s", n))
return nil, false
}
if !t.Equal(&shaderir.Type{}) && !canAssign(&t, &ts[0], es[0].Const) {
s.addError(vs.Pos(), fmt.Sprintf("cannot use %v as %s value in constant declaration", es[0].Const, t.String()))
return nil, false
}
c := es[0].Const
switch t.Main {
case shaderir.Bool:
case shaderir.Int:
c = gconstant.ToInt(c)
case shaderir.Float:
c = gconstant.ToFloat(c)
}
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cs = append(cs, constant{
name: name,
typ: t,
value: c,
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})
}
return cs, true
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}
func (cs *compileState) parseFuncParams(block *block, fname string, d *ast.FuncDecl) (in, out []variable, ret shaderir.Type) {
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for _, f := range d.Type.Params.List {
t, ok := cs.parseType(block, fname, f.Type)
if !ok {
return
}
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for _, n := range f.Names {
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in = append(in, variable{
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name: n.Name,
typ: t,
})
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}
}
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if d.Type.Results == nil {
return
}
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for _, f := range d.Type.Results.List {
t, ok := cs.parseType(block, fname, f.Type)
if !ok {
return
}
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if len(f.Names) == 0 {
out = append(out, variable{
name: "",
typ: t,
})
} else {
for _, n := range f.Names {
out = append(out, variable{
name: n.Name,
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typ: t,
})
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}
}
}
// If there is only one returning value, it is treated as a returning value.
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// Only if not the fragment entrypoint.
// An array cannot be a returning value, especially for HLSL (#2923).
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if fname != cs.fragmentEntry && len(out) == 1 && out[0].name == "" && out[0].typ.Main != shaderir.Array {
ret = out[0].typ
out = nil
}
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return
}
func (cs *compileState) parseFunc(block *block, d *ast.FuncDecl) (function, bool) {
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if d.Name == nil {
cs.addError(d.Pos(), "function must have a name")
return function{}, false
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}
if d.Name.Name == "init" {
cs.addError(d.Pos(), "init function is not implemented")
return function{}, false
}
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if d.Body == nil {
cs.addError(d.Pos(), "function must have a body")
return function{}, false
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}
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inParams, outParams, returnType := cs.parseFuncParams(block, d.Name.Name, d)
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checkVaryings := func(vs []variable) {
if len(cs.ir.Varyings) != len(vs) {
cs.addError(d.Pos(), "the number of vertex entry point's returning values and the number of fragment entry point's params must be the same")
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return
}
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for i, t := range cs.ir.Varyings {
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if t.Main != vs[i].typ.Main {
cs.addError(d.Pos(), "vertex entry point's returning value types and fragment entry point's param types must match")
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}
}
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}
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if block == &cs.global {
switch d.Name.Name {
case cs.vertexEntry:
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for _, v := range inParams {
cs.ir.Attributes = append(cs.ir.Attributes, v.typ)
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}
// For the vertex entry, a parameter (variable) is used as a returning value.
// For example, GLSL doesn't treat gl_Position as a returning value.
// TODO: This can be resolved by having an indirect function like what the fragment entry already does.
// See internal/shaderir/glsl.adjustProgram.
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if len(outParams) == 0 {
outParams = append(outParams, variable{
typ: shaderir.Type{Main: shaderir.Vec4},
})
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}
// The first out-param is treated as gl_Position in GLSL.
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if outParams[0].typ.Main != shaderir.Vec4 {
cs.addError(d.Pos(), "vertex entry point must have at least one returning vec4 value for a position")
return function{}, false
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}
if cs.varyingParsed {
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checkVaryings(outParams[1:])
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} else {
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for _, v := range outParams[1:] {
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// TODO: Check that these params are not arrays or structs
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cs.ir.Varyings = append(cs.ir.Varyings, v.typ)
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}
}
cs.varyingParsed = true
case cs.fragmentEntry:
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if len(inParams) == 0 {
cs.addError(d.Pos(), "fragment entry point must have at least one vec4 parameter for a position")
return function{}, false
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}
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if inParams[0].typ.Main != shaderir.Vec4 {
cs.addError(d.Pos(), "fragment entry point must have at least one vec4 parameter for a position")
return function{}, false
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}
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// The first out-param is treated as fragColor0 in GLSL.
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for i := range outParams {
if outParams[i].typ.Main != shaderir.Vec4 {
cs.addError(d.Pos(), "fragment entry point must only have vec4 return values for colors")
return function{}, false
}
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}
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// Adjust the number of textures to write to
cs.ir.ColorsOutCount = len(outParams)
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if cs.varyingParsed {
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checkVaryings(inParams[1:])
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} else {
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for _, v := range inParams[1:] {
cs.ir.Varyings = append(cs.ir.Varyings, v.typ)
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}
}
cs.varyingParsed = true
}
}
b, ok := cs.parseBlock(block, d.Name.Name, d.Body.List, inParams, outParams, returnType, true)
if !ok {
return function{}, false
}
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if len(outParams) > 0 || returnType.Main != shaderir.None {
var hasReturn func(stmts []shaderir.Stmt) bool
hasReturn = func(stmts []shaderir.Stmt) bool {
for _, stmt := range stmts {
if stmt.Type == shaderir.Return {
return true
}
for _, b := range stmt.Blocks {
if hasReturn(b.Stmts) {
return true
}
}
}
return false
}
if !hasReturn(b.ir.Stmts) {
cs.addError(d.Pos(), fmt.Sprintf("function %s must have a return statement but not", d.Name))
return function{}, false
}
}
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var inT, outT []shaderir.Type
for _, v := range inParams {
inT = append(inT, v.typ)
}
for _, v := range outParams {
outT = append(outT, v.typ)
}
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return function{
name: d.Name.Name,
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ir: shaderir.Func{
InParams: inT,
OutParams: outT,
Return: returnType,
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Block: b.ir,
},
}, true
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}
func (cs *compileState) parseBlock(outer *block, fname string, stmts []ast.Stmt, inParams, outParams []variable, returnType shaderir.Type, checkLocalVariableUsage bool) (*block, bool) {
var vars []variable
if outer == &cs.global {
vars = make([]variable, 0, len(inParams)+len(outParams))
vars = append(vars, inParams...)
vars = append(vars, outParams...)
}
var offset int
for b := outer; b != nil; b = b.outer {
offset += len(b.vars)
}
if outer == &cs.global {
offset += len(inParams) + len(outParams)
}
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block := &block{
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vars: vars,
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outer: outer,
ir: &shaderir.Block{
LocalVarIndexOffset: offset,
},
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}
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defer func() {
var offset int
if outer == &cs.global {
offset = len(inParams) + len(outParams)
}
for _, v := range block.vars[offset:] {
if v.forLoopCounter {
block.ir.LocalVars = append(block.ir.LocalVars, shaderir.Type{})
continue
}
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block.ir.LocalVars = append(block.ir.LocalVars, v.typ)
}
}()
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if outer.outer == nil && len(outParams) > 0 && outParams[0].name != "" {
for i := range outParams {
block.ir.Stmts = append(block.ir.Stmts, shaderir.Stmt{
Type: shaderir.Init,
InitIndex: len(inParams) + i,
})
}
}
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for _, stmt := range stmts {
ss, ok := cs.parseStmt(block, fname, stmt, inParams, outParams, returnType)
if !ok {
return nil, false
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}
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block.ir.Stmts = append(block.ir.Stmts, ss...)
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}
if checkLocalVariableUsage && len(block.unusedVars) > 0 {
for idx, pos := range block.unusedVars {
cs.addError(pos, fmt.Sprintf("local variable %s is not used", block.vars[idx].name))
}
return nil, false
}
return block, true
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}