mirror of
https://github.com/hajimehoshi/ebiten.git
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132 lines
3.3 KiB
Go
132 lines
3.3 KiB
Go
// Copyright 2019 The Ebiten Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Package vector provides functions for vector graphics rendering.
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//
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// This package is under experiments and the API might be changed with breaking backward compatibility.
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package vector
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import (
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"image/color"
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"github.com/hajimehoshi/ebiten"
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"github.com/hajimehoshi/ebiten/vector/internal/math"
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)
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var emptyImage *ebiten.Image
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func init() {
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emptyImage, _ = ebiten.NewImage(1, 1, ebiten.FilterDefault)
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emptyImage.Fill(color.White)
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}
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// Path represents a collection of path segments.
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type Path struct {
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segs [][]math.Point
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cur math.Point
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}
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// MoveTo skips the current position of the path to the given position (x, y) without adding any strokes.
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func (p *Path) MoveTo(x, y float32) {
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p.cur = math.Point{X: x, Y: y}
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p.segs = append(p.segs, []math.Point{p.cur})
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}
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// LineTo adds a line segument to the path, which starts from the current position and ends to the given position (x, y).
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//
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// LineTo updates the current position to (x, y).
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func (p *Path) LineTo(x, y float32) {
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if len(p.segs) == 0 {
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p.segs = append(p.segs, []math.Point{p.cur})
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}
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p.segs[len(p.segs)-1] = append(p.segs[len(p.segs)-1], math.Point{X: x, Y: y})
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p.cur = math.Point{X: x, Y: y}
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}
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func nseg(x0, y0, x1, y1 float32) int {
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distx := x1 - x0
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if distx < 0 {
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distx = -distx
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}
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disty := y1 - y0
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if disty < 0 {
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disty = -disty
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}
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dist := distx
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if dist < disty {
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dist = disty
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}
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num := 1
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for float32(num) < dist {
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num *= 2
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}
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return num
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}
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func (p *Path) QuadraticCurveTo(cpx, cpy, x, y float32) {
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c := p.cur
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num := nseg(c.X, c.Y, x, y)
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for t := float32(0.0); t <= 1; t += 1.0 / float32(num) {
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xf := (1-t)*(1-t)*c.X + 2*t*(1-t)*cpx + t*t*x
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yf := (1-t)*(1-t)*c.Y + 2*t*(1-t)*cpy + t*t*y
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p.LineTo(xf, yf)
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}
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}
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func (p *Path) BezierCurveTo(cp0x, cp0y, cp1x, cp1y, x, y float32) {
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c := p.cur
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num := nseg(c.X, c.Y, x, y)
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for t := float32(0.0); t <= 1; t += 1.0 / float32(num) {
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xf := (1-t)*(1-t)*(1-t)*c.X + 3*(1-t)*(1-t)*t*cp0x + 3*(1-t)*t*t*cp1x + t*t*t*x
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yf := (1-t)*(1-t)*(1-t)*c.Y + 3*(1-t)*(1-t)*t*cp0y + 3*(1-t)*t*t*cp1y + t*t*t*y
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p.LineTo(xf, yf)
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}
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}
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func (p *Path) Fill(dst *ebiten.Image, clr color.Color) {
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var vertices []ebiten.Vertex
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var indices []uint16
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r, g, b, a := clr.RGBA()
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var rf, gf, bf, af float32
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if a > 0 {
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rf = float32(r) / float32(a)
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gf = float32(g) / float32(a)
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bf = float32(b) / float32(a)
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af = float32(a) / 0xffff
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}
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var base uint16
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for _, seg := range p.segs {
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for _, pt := range seg {
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vertices = append(vertices, ebiten.Vertex{
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DstX: pt.X,
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DstY: pt.Y,
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SrcX: 0,
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SrcY: 0,
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ColorR: rf,
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ColorG: gf,
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ColorB: bf,
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ColorA: af,
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})
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}
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for _, idx := range math.Triangulate(seg) {
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indices = append(indices, idx+base)
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}
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base += uint16(len(seg))
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}
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dst.DrawTriangles(vertices, indices, emptyImage, nil)
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}
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