mirror of
https://github.com/bloeys/nmage.git
synced 2025-12-29 13:28:20 +00:00
116 lines
2.3 KiB
Go
Executable File
116 lines
2.3 KiB
Go
Executable File
package main
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import (
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"fmt"
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"time"
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"github.com/veandco/go-sdl2/sdl"
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)
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const (
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winWidth int32 = 800
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winHeight int32 = 600
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)
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var (
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isRunning = true
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window *sdl.Window
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)
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func main() {
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err := sdl.Init(sdl.INIT_EVERYTHING)
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if err != nil {
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panic("Failed to init SDL. Err: " + err.Error())
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}
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defer sdl.Quit()
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window, err = sdl.CreateWindow(
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"test",
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sdl.WINDOWPOS_CENTERED,
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sdl.WINDOWPOS_CENTERED,
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winWidth,
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winHeight,
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sdl.WINDOW_SHOWN)
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if err != nil {
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panic("Failed to create window. Err: " + err.Error())
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}
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defer window.Destroy()
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rend, err := sdl.CreateRenderer(window, -1, sdl.RENDERER_ACCELERATED)
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if err != nil {
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panic("Creating renderer failed. Err: " + err.Error())
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}
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defer rend.Destroy()
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tex, err := rend.CreateTexture(sdl.PIXELFORMAT_ABGR8888, 0, winWidth, winHeight)
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if err != nil {
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panic(err)
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}
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//x4 to allow for RGBA
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pixels := make([]byte, winHeight*winWidth*4)
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for y := 0; y < int(winHeight); y++ {
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for x := 0; x < int(winWidth); x++ {
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c := sdl.Color{
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R: byte(int(float64(x)/float64(winWidth)*256) % 256),
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G: byte(int(float64(y)/float64(winHeight)*256) % 256),
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}
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setPixel(x, y, c, pixels)
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}
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}
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//Update texture with new pixel values
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tex.Update(nil, pixels, int(winWidth)*4)
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//Copy texture to renderer
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rend.Copy(tex, nil, nil)
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//Blit
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rend.Present()
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var fps float32 = 60
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var dt float32 = 1.0 / 60.0
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var dtLimit float32 = 1.0 / 120.0
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for isRunning {
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frameStartTime := time.Now()
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handleEvents()
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//If FPS is more than 120 then limit to that
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dt = float32(time.Since(frameStartTime).Seconds())
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if dt < dtLimit {
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sdl.Delay(8 - uint32(dt*1000))
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dt = float32(time.Since(frameStartTime).Seconds())
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}
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//Display FPS is the average of the FPS of this frame and the last frame
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fps = (fps + 1/dt) / 2
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window.SetTitle(fmt.Sprintf("FPS: %.2f; dt: %.3f", fps, dt))
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}
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}
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func handleEvents() {
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for event := sdl.PollEvent(); event != nil; event = sdl.PollEvent() {
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switch e := event.(type) {
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case *sdl.QuitEvent:
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println("Quit at ", e.Timestamp)
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isRunning = false
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}
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}
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}
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//handleEvents assumes sdl.PIXELFORMAT_ABGR8888
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func setPixel(x, y int, c sdl.Color, pixels []byte) {
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index := (y*int(winWidth) + x) * 4
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pixels[index] = c.R
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pixels[index+1] = c.G
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pixels[index+2] = c.B
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pixels[index+3] = c.A
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}
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