shader: Implement an array variable

Updates #1235

internal/shader/shader.go

@@ -211,7 +211,7 @@ func (cs *compileState) parse(f *ast.File) {
 			continue
 		}
 
-		inParams, outParams := cs.parseFuncParams(fd)
+		inParams, outParams := cs.parseFuncParams(&cs.global, fd)
 		var inT, outT []shaderir.Type
 		for _, v := range inParams {
 			inT = append(inT, v.typ)
@@ -260,7 +260,7 @@ func (cs *compileState) parseDecl(b *block, d ast.Decl) ([]shaderir.Stmt, bool)
 			// TODO: Parse other types
 			for _, s := range d.Specs {
 				s := s.(*ast.TypeSpec)
-				t := cs.parseType(s.Type)
+				t := cs.parseType(b, s.Type)
 				b.types = append(b.types, typ{
 					name: s.Name.Name,
 					ir:   t,
@@ -269,7 +269,7 @@ func (cs *compileState) parseDecl(b *block, d ast.Decl) ([]shaderir.Stmt, bool)
 		case token.CONST:
 			for _, s := range d.Specs {
 				s := s.(*ast.ValueSpec)
-				cs := cs.parseConstant(s)
+				cs := cs.parseConstant(b, s)
 				b.consts = append(b.consts, cs...)
 			}
 		case token.VAR:
@@ -385,7 +385,7 @@ func (s *compileState) parseVariable(block *block, vs *ast.ValueSpec) ([]variabl
 
 	var declt shaderir.Type
 	if vs.Type != nil {
-		declt = s.parseType(vs.Type)
+		declt = s.parseType(block, vs.Type)
 	}
 
 	var (
@@ -480,10 +480,10 @@ func (s *compileState) parseVariable(block *block, vs *ast.ValueSpec) ([]variabl
 	return vars, inits, stmts, true
 }
 
-func (s *compileState) parseConstant(vs *ast.ValueSpec) []constant {
+func (s *compileState) parseConstant(block *block, vs *ast.ValueSpec) []constant {
 	var t shaderir.Type
 	if vs.Type != nil {
-		t = s.parseType(vs.Type)
+		t = s.parseType(block, vs.Type)
 	}
 
 	var cs []constant
@@ -497,9 +497,9 @@ func (s *compileState) parseConstant(vs *ast.ValueSpec) []constant {
 	return cs
 }
 
-func (cs *compileState) parseFuncParams(d *ast.FuncDecl) (in, out []variable) {
+func (cs *compileState) parseFuncParams(block *block, d *ast.FuncDecl) (in, out []variable) {
 	for _, f := range d.Type.Params.List {
-		t := cs.parseType(f.Type)
+		t := cs.parseType(block, f.Type)
 		for _, n := range f.Names {
 			in = append(in, variable{
 				name: n.Name,
@@ -513,7 +513,7 @@ func (cs *compileState) parseFuncParams(d *ast.FuncDecl) (in, out []variable) {
 	}
 
 	for _, f := range d.Type.Results.List {
-		t := cs.parseType(f.Type)
+		t := cs.parseType(block, f.Type)
 		if len(f.Names) == 0 {
 			out = append(out, variable{
 				name: "",
@@ -541,7 +541,7 @@ func (cs *compileState) parseFunc(block *block, d *ast.FuncDecl) (function, bool
 		return function{}, false
 	}
 
-	inParams, outParams := cs.parseFuncParams(d)
+	inParams, outParams := cs.parseFuncParams(block, d)
 
 	checkVaryings := func(vs []variable) {
 		if len(cs.ir.Varyings) != len(vs) {

internal/shader/testdata/array.expected.vs

@@ -0,0 +1 @@
+uniform vec2[4] U0;

internal/shader/testdata/array.go

@@ -0,0 +1,3 @@
+package main
+
+var Array [4]vec2

internal/shader/type.go

@@ -17,13 +17,12 @@ package shader
 import (
 	"fmt"
 	"go/ast"
+	gconstant "go/constant"
 
 	"github.com/hajimehoshi/ebiten/internal/shaderir"
 )
 
-// TODO: What about array types?
-
-func (cs *compileState) parseType(expr ast.Expr) shaderir.Type {
+func (cs *compileState) parseType(block *block, expr ast.Expr) shaderir.Type {
 	switch t := expr.(type) {
 	case *ast.Ident:
 		switch t.Name {
@@ -49,6 +48,41 @@ func (cs *compileState) parseType(expr ast.Expr) shaderir.Type {
 			cs.addError(t.Pos(), fmt.Sprintf("unexpected type: %s", t.Name))
 			return shaderir.Type{}
 		}
+	case *ast.ArrayType:
+		if t.Len == nil {
+			cs.addError(t.Pos(), fmt.Sprintf("array length must be specified"))
+			return shaderir.Type{}
+		}
+		// TODO: Parse ellipsis
+
+		exprs, _, _, ok := cs.parseExpr(block, t.Len)
+		if !ok {
+			return shaderir.Type{}
+		}
+		if len(exprs) != 1 {
+			cs.addError(t.Pos(), fmt.Sprintf("invalid length of array"))
+			return shaderir.Type{}
+		}
+		if exprs[0].Type != shaderir.NumberExpr {
+			cs.addError(t.Pos(), fmt.Sprintf("length of array must be a constant number"))
+			return shaderir.Type{}
+		}
+		len, ok := gconstant.Int64Val(exprs[0].Const)
+		if !ok {
+			cs.addError(t.Pos(), fmt.Sprintf("length of array must be an integer"))
+			return shaderir.Type{}
+		}
+
+		elm := cs.parseType(block, t.Elt)
+		if elm.Main == shaderir.Array {
+			cs.addError(t.Pos(), fmt.Sprintf("array of array is forbidden"))
+			return shaderir.Type{}
+		}
+		return shaderir.Type{
+			Main:   shaderir.Array,
+			Sub:    []shaderir.Type{elm},
+			Length: int(len),
+		}
 	case *ast.StructType:
 		cs.addError(t.Pos(), "struct is not implemented")
 		return shaderir.Type{}

internal/shaderir/glsl.go

@@ -172,12 +172,10 @@ func (p *Program) glslType(t *Type) string {
 	switch t.Main {
 	case None:
 		return "void"
-	case Array:
-		panic("not implemented")
 	case Struct:
 		return p.structName(t)
 	default:
-		return t.Main.Glsl()
+		return t.Glsl()
 	}
 }
 
@@ -185,12 +183,10 @@ func (p *Program) glslVarDecl(t *Type, varname string) string {
 	switch t.Main {
 	case None:
 		return "?(none)"
-	case Array:
-		panic("not implemented")
 	case Struct:
 		return fmt.Sprintf("%s %s", p.structName(t), varname)
 	default:
-		return fmt.Sprintf("%s %s", t.Main.Glsl(), varname)
+		return fmt.Sprintf("%s %s", t.Glsl(), varname)
 	}
 }
 
@@ -432,7 +428,7 @@ func (p *Program) glslBlock(topBlock, block *Block, level int, localVarIndex int
 				op = fmt.Sprintf("?(unexpected op: %s)", string(s.ForOp))
 			}
 
-			t := s.ForVarType.Main
+			t := s.ForVarType
 			init := constantToNumberLiteral(ct, s.ForInit)
 			end := constantToNumberLiteral(ct, s.ForEnd)
 			lines = append(lines, fmt.Sprintf("%sfor (%s %s = %s; %s %s %s; %s) {", idt, t.Glsl(), v, init, v, op, end, delta))

internal/shaderir/type.go

@@ -85,6 +85,17 @@ func (t *Type) serialize() string {
 	return t.String()
 }
 
+func (t *Type) Glsl() string {
+	switch t.Main {
+	case Array:
+		return fmt.Sprintf("%s[%d]", t.Sub[0].Glsl(), t.Length)
+	case Struct:
+		panic("shaderir: a struct is not implemented")
+	default:
+		return t.Main.glsl()
+	}
+}
+
 type BasicType int
 
 const (
@@ -102,7 +113,7 @@ const (
 	Struct
 )
 
-func (t BasicType) Glsl() string {
+func (t BasicType) glsl() string {
 	switch t {
 	case None:
 		return "?(none)"
@@ -125,7 +136,6 @@ func (t BasicType) Glsl() string {
 	case Mat4:
 		return "mat4"
 	case Array:
-		// First-class array is not available on GLSL ES 2.
 		return "?(array)"
 	case Struct:
 		return "?(struct)"