ebiten/examples/shader/main.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.
// +build example jsgo
package main
import (
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"bytes"
"image"
_ "image/jpeg"
"log"
"github.com/hajimehoshi/ebiten"
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"github.com/hajimehoshi/ebiten/ebitenutil"
"github.com/hajimehoshi/ebiten/examples/resources/images"
"github.com/hajimehoshi/ebiten/inpututil"
)
const (
screenWidth = 640
screenHeight = 480
)
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var gophersImage *ebiten.Image
func init() {
// Decode image from a byte slice instead of a file so that
// this example works in any working directory.
// If you want to use a file, there are some options:
// 1) Use os.Open and pass the file to the image decoder.
// This is a very regular way, but doesn't work on browsers.
// 2) Use ebitenutil.OpenFile and pass the file to the image decoder.
// This works even on browsers.
// 3) Use ebitenutil.NewImageFromFile to create an ebiten.Image directly from a file.
// This also works on browsers.
img, _, err := image.Decode(bytes.NewReader(images.Gophers_jpg))
if err != nil {
log.Fatal(err)
}
gophersImage, _ = ebiten.NewImageFromImage(img, ebiten.FilterDefault)
}
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var shaderSrcs = [][]byte{
default_go,
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image_go,
}
type Game struct {
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shaders map[int]*ebiten.Shader
idx int
time int
}
func (g *Game) Update(screen *ebiten.Image) error {
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g.time++
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if inpututil.IsKeyJustPressed(ebiten.KeyDown) {
g.idx++
g.idx %= len(shaderSrcs)
}
if inpututil.IsKeyJustPressed(ebiten.KeyUp) {
g.idx += len(shaderSrcs) - 1
g.idx %= len(shaderSrcs)
}
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if g.shaders == nil {
g.shaders = map[int]*ebiten.Shader{}
}
if _, ok := g.shaders[g.idx]; !ok {
s, err := ebiten.NewShader([]byte(shaderSrcs[g.idx]))
if err != nil {
return err
}
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g.shaders[g.idx] = s
}
return nil
}
func (g *Game) Draw(screen *ebiten.Image) {
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s, ok := g.shaders[g.idx]
if !ok {
return
}
w, h := screen.Size()
vs := []ebiten.Vertex{
{
DstX: 0,
DstY: 0,
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SrcX: 0,
SrcY: 0,
},
{
DstX: float32(w),
DstY: 0,
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SrcX: float32(w),
SrcY: 0,
},
{
DstX: 0,
DstY: float32(h),
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SrcX: 0,
SrcY: float32(h),
},
{
DstX: float32(w),
DstY: float32(h),
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SrcX: float32(w),
SrcY: float32(h),
},
}
is := []uint16{0, 1, 2, 1, 2, 3}
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cx, cy := ebiten.CursorPosition()
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op := &ebiten.DrawTrianglesWithShaderOptions{}
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op.Uniforms = []interface{}{
float32(g.time) / 60, // Time
[]float32{float32(cx), float32(cy)}, // Cursor
}
if g.idx != 0 {
op.Uniforms = append(op.Uniforms,
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gophersImage, // Image
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)
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}
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screen.DrawTrianglesWithShader(vs, is, s, op)
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msg := "Press Up/Down to switch the shader."
ebitenutil.DebugPrint(screen, msg)
}
func (g *Game) Layout(outsideWidth, outsideHeight int) (int, int) {
return screenWidth, screenHeight
}
func main() {
ebiten.SetWindowSize(screenWidth, screenHeight)
ebiten.SetWindowTitle("Shader (Ebiten Demo)")
if err := ebiten.RunGame(&Game{}); err != nil {
log.Fatal(err)
}
}