mirror of
https://github.com/hajimehoshi/ebiten.git
synced 2024-11-10 13:07:26 +01:00
141 lines
2.9 KiB
Go
141 lines
2.9 KiB
Go
// Copyright 2018 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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// +build example jsgo
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package main
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import (
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"fmt"
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"image/color"
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"log"
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"math"
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"github.com/hajimehoshi/ebiten"
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"github.com/hajimehoshi/ebiten/ebitenutil"
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"github.com/hajimehoshi/ebiten/inpututil"
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)
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const (
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screenWidth = 640
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screenHeight = 480
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)
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var (
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emptyImage, _ = ebiten.NewImage(16, 16, ebiten.FilterDefault)
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)
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func init() {
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emptyImage.Fill(color.White)
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}
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var (
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vertices []ebiten.Vertex
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ngon = 10
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prevNgon = 0
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)
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func genVertices(num int) []ebiten.Vertex {
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const (
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centerX = screenWidth / 2
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centerY = screenHeight / 2
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r = 160
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)
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vs := []ebiten.Vertex{}
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for i := 0; i < num; i++ {
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rate := float64(i) / float64(num)
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cr := 0.0
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cg := 0.0
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cb := 0.0
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if rate < 1.0/3.0 {
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cb = 2 - 2*(rate*3)
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cr = 2 * (rate * 3)
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}
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if 1.0/3.0 <= rate && rate < 2.0/3.0 {
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cr = 2 - 2*(rate-1.0/3.0)*3
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cg = 2 * (rate - 1.0/3.0) * 3
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}
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if 2.0/3.0 <= rate {
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cg = 2 - 2*(rate-2.0/3.0)*3
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cb = 2 * (rate - 2.0/3.0) * 3
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}
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vs = append(vs, ebiten.Vertex{
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DstX: float32(r*math.Cos(2*math.Pi*rate)) + centerX,
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DstY: float32(r*math.Sin(2*math.Pi*rate)) + centerY,
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SrcX: 0,
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SrcY: 0,
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ColorR: float32(cr),
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ColorG: float32(cg),
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ColorB: float32(cb),
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ColorA: 1,
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})
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}
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vs = append(vs, ebiten.Vertex{
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DstX: centerX,
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DstY: centerY,
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SrcX: 0,
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SrcY: 0,
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ColorR: 1,
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ColorG: 1,
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ColorB: 1,
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ColorA: 1,
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})
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return vs
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}
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func update(screen *ebiten.Image) error {
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if inpututil.IsKeyJustPressed(ebiten.KeyLeft) {
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ngon--
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if ngon < 1 {
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ngon = 1
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}
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}
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if inpututil.IsKeyJustPressed(ebiten.KeyRight) {
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ngon++
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if ngon > 120 {
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ngon = 120
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}
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}
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if prevNgon != ngon || len(vertices) == 0 {
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vertices = genVertices(ngon)
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prevNgon = ngon
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}
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if ebiten.IsDrawingSkipped() {
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return nil
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}
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op := &ebiten.DrawTrianglesOptions{}
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indices := []uint16{}
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for i := 0; i < ngon; i++ {
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indices = append(indices, uint16(i), uint16(i+1)%uint16(ngon), uint16(ngon))
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}
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screen.DrawTriangles(vertices, indices, emptyImage, op)
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msg := fmt.Sprintf("TPS: %0.2f\n%d-gon\nPress <- or -> to change the number of the vertices", ebiten.CurrentTPS(), ngon)
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ebitenutil.DebugPrint(screen, msg)
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return nil
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}
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func main() {
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if err := ebiten.Run(update, screenWidth, screenHeight, 1, "Polygons (Ebiten Demo)"); err != nil {
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log.Fatal(err)
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}
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}
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