ebiten/internal/packing/packing.go
2018-03-17 17:41:36 +09:00

301 lines
5.7 KiB
Go

// Copyright 2018 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 packing offers a packing algorithm in 2D space.
package packing
import (
"errors"
)
const (
minSize = 1
)
type Page struct {
root *Node
size int
maxSize int
}
func NewPage(initSize int, maxSize int) *Page {
return &Page{
size: initSize,
maxSize: maxSize,
}
}
func (p *Page) IsEmpty() bool {
if p.root == nil {
return true
}
return !p.root.used && p.root.child0 == nil && p.root.child1 == nil
}
type Node struct {
x int
y int
width int
height int
used bool
parent *Node
child0 *Node
child1 *Node
}
func (n *Node) canFree() bool {
if n.used {
return false
}
if n.child0 == nil && n.child1 == nil {
return true
}
return n.child0.canFree() && n.child1.canFree()
}
func (n *Node) Region() (x, y, width, height int) {
return n.x, n.y, n.width, n.height
}
// square returns a float value indicating how much the given rectangle is close to a square.
// If the given rectangle is square, this return 1 (maximum value).
// Otherwise, this returns a value in [0, 1).
func square(width, height int) float64 {
if width == 0 && height == 0 {
return 0
}
if width <= height {
return float64(width) / float64(height)
}
return float64(height) / float64(width)
}
func (p *Page) alloc(n *Node, width, height int) *Node {
if n.width < width || n.height < height {
return nil
}
if n.used {
return nil
}
if n.child0 == nil && n.child1 == nil {
if n.width == width && n.height == height {
n.used = true
return n
}
if square(n.width-width, n.height) >= square(n.width, n.height-height) {
// Split vertically
n.child0 = &Node{
x: n.x,
y: n.y,
width: width,
height: n.height,
parent: n,
}
n.child1 = &Node{
x: n.x + width,
y: n.y,
width: n.width - width,
height: n.height,
parent: n,
}
} else {
// Split holizontally
n.child0 = &Node{
x: n.x,
y: n.y,
width: n.width,
height: height,
parent: n,
}
n.child1 = &Node{
x: n.x,
y: n.y + height,
width: n.width,
height: n.height - height,
parent: n,
}
}
return p.alloc(n.child0, width, height)
}
if n.child0 == nil || n.child1 == nil {
panic("not reached")
}
if node := p.alloc(n.child0, width, height); node != nil {
return node
}
if node := p.alloc(n.child1, width, height); node != nil {
return node
}
return nil
}
func (p *Page) Size() int {
return p.size
}
func (p *Page) Alloc(width, height int) *Node {
if width <= 0 || height <= 0 {
panic("bsp: width and height must > 0")
}
if p.root == nil {
p.root = &Node{
width: p.size,
height: p.size,
}
}
if width < minSize {
width = minSize
}
if height < minSize {
height = minSize
}
n := p.alloc(p.root, width, height)
return n
}
func (p *Page) Free(node *Node) {
if node.child0 != nil || node.child1 != nil {
panic("bsp: can't free the node including children")
}
node.used = false
if node.parent == nil {
return
}
if node.parent.child0 == nil || node.parent.child1 == nil {
panic("not reached")
}
if node.parent.child0.canFree() && node.parent.child1.canFree() {
node.parent.child0 = nil
node.parent.child1 = nil
p.Free(node.parent)
}
}
func walk(n *Node, f func(n *Node) error) error {
if err := f(n); err != nil {
return err
}
if n.child0 != nil {
if err := walk(n.child0, f); err != nil {
return err
}
}
if n.child1 != nil {
if err := walk(n.child1, f); err != nil {
return err
}
}
return nil
}
func (p *Page) Extend() bool {
if p.size >= p.maxSize {
return false
}
newSize := p.size * 2
edgeNodes := []*Node{}
abort := errors.New("abort")
aborted := false
_ = walk(p.root, func(n *Node) error {
if n.x+n.width < p.size && n.y+n.height < p.size {
return nil
}
if n.used {
aborted = true
return abort
}
edgeNodes = append(edgeNodes, n)
return nil
})
if aborted {
leftUpper := p.root
leftLower := &Node{
x: 0,
y: p.size,
width: p.size,
height: newSize - p.size,
}
left := &Node{
x: 0,
y: 0,
width: p.size,
height: p.size,
child0: leftUpper,
child1: leftLower,
}
leftUpper.parent = left
leftLower.parent = left
right := &Node{
x: p.size,
y: 0,
width: newSize - p.size,
height: newSize,
}
p.root = &Node{
x: 0,
y: 0,
width: newSize,
height: newSize,
child0: left,
child1: right,
}
left.parent = p.root
right.parent = p.root
} else {
for _, n := range edgeNodes {
if n.x+n.width == p.size {
n.width += newSize - p.size
}
if n.y+n.height == p.size {
n.height += newSize - p.size
}
}
}
p.size = newSize
return true
}
func (n *Node) clone() *Node {
if n == nil {
return nil
}
cloned := &Node{
x: n.x,
y: n.y,
width: n.width,
height: n.height,
used: n.used,
child0: n.child0.clone(),
child1: n.child1.clone(),
}
if cloned.child0 != nil {
cloned.child0.parent = cloned
}
if cloned.child1 != nil {
cloned.child1.parent = cloned
}
return cloned
}
func (p *Page) Clone() *Page {
return &Page{
root: p.root.clone(),
size: p.size,
maxSize: p.maxSize,
}
}