Example #13: setting various blending modes

lesson7/sdl/introduction/test13.go

@@ -0,0 +1,67 @@
+package main
+
+import (
+	"github.com/veandco/go-sdl2/img"
+	"github.com/veandco/go-sdl2/sdl"
+)
+
+const (
+	width  = 640
+	height = 480
+)
+
+func main() {
+	if err := sdl.Init(sdl.INIT_VIDEO); err != nil {
+		panic(err)
+	}
+	defer sdl.Quit()
+
+	window, err := sdl.CreateWindow("SDL2 example #13", sdl.WINDOWPOS_UNDEFINED, sdl.WINDOWPOS_UNDEFINED,
+		width, height, sdl.WINDOW_SHOWN)
+	if err != nil {
+		panic(err)
+	}
+	defer window.Destroy()
+
+	primarySurface, err := window.GetSurface()
+	if err != nil {
+		panic(err)
+	}
+
+	image, err := img.Load("globe.png")
+	if err != nil {
+		panic(err)
+	}
+	defer image.Free()
+
+	primarySurface.FillRect(nil, sdl.MapRGB(primarySurface.Format, 192, 255, 192))
+
+	dstRect := sdl.Rect{}
+	dstRect.Y = 10
+
+	for y := 0; y < 4; y++ {
+		image.SetAlphaMod(byte(y * 64))
+
+		image.SetBlendMode(sdl.BLENDMODE_NONE)
+		dstRect.X = 10
+		image.Blit(nil, primarySurface, &dstRect)
+
+		image.SetBlendMode(sdl.BLENDMODE_BLEND)
+		dstRect.X += 100
+		image.Blit(nil, primarySurface, &dstRect)
+
+		image.SetBlendMode(sdl.BLENDMODE_ADD)
+		dstRect.X += 100
+		image.Blit(nil, primarySurface, &dstRect)
+
+		image.SetBlendMode(sdl.BLENDMODE_MOD)
+		dstRect.X += 100
+		image.Blit(nil, primarySurface, &dstRect)
+
+		dstRect.Y += 100
+	}
+
+	window.UpdateSurface()
+
+	sdl.Delay(5000)
+}