examples: add render-geometry example

Signed-off-by: Lilis Iskandar <lilis@veand.co>

examples/render-geometry/render-geometry.go

@@ -0,0 +1,61 @@
+package main
+
+import (
+	"log"
+	"unsafe"
+
+	"github.com/veandco/go-sdl2/sdl"
+)
+
+// Whether to use RenderGeometryRaw or not
+const raw = false
+
+func main() {
+	sdl.Init(sdl.INIT_EVERYTHING)
+	defer sdl.Quit()
+
+	window, err := sdl.CreateWindow("Test RenderGeometryRaw", sdl.WINDOWPOS_UNDEFINED, sdl.WINDOWPOS_UNDEFINED, 800, 600, sdl.WINDOW_SHOWN)
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer window.Destroy()
+
+	renderer, err := sdl.CreateRenderer(window, -1, sdl.RENDERER_SOFTWARE)
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer renderer.Destroy()
+
+	vertices := []sdl.Vertex{
+		{sdl.FPoint{400, 150}, sdl.Color{255, 0, 0, 255}, sdl.FPoint{0, 0}},
+		{sdl.FPoint{200, 450}, sdl.Color{0, 0, 255, 255}, sdl.FPoint{0, 0}},
+		{sdl.FPoint{600, 450}, sdl.Color{0, 255, 0, 255}, sdl.FPoint{0, 0}},
+	}
+
+	if raw {
+		log.Println("Using RenderGeometryRaw")
+	} else {
+		log.Println("Using RenderGeometry")
+	}
+
+	running := true
+	for running {
+		for event := sdl.PollEvent(); event != nil; event = sdl.PollEvent() {
+			switch event.(type) {
+			case *sdl.QuitEvent:
+				running = false
+			}
+		}
+
+		renderer.SetDrawColor(0, 0, 0, sdl.ALPHA_OPAQUE)
+		renderer.Clear()
+		if raw {
+			renderer.RenderGeometryRaw(nil, (*float32)(unsafe.Pointer(&vertices[0])), 20, (*sdl.Color)(unsafe.Add(unsafe.Pointer(&vertices[0]), 8)), 20, (*float32)(unsafe.Add(unsafe.Pointer(&vertices[0]), 12)), 20, len(vertices), nil, 0, 0)
+		} else {
+			renderer.RenderGeometry(nil, vertices, nil)
+		}
+		renderer.Present()
+
+		sdl.Delay(33)
+	}
+}