Added depth test function and 3D demo.

demo/model/model.go

@@ -0,0 +1,66 @@
+package main
+
+import (
+	"github.com/DeKugelschieber/go-game"
+)
+
+const (
+	assets_dir = "src/github.com/DeKugelschieber/go-game/demo/model/assets"
+)
+
+type Game struct {
+	model *goga.Model
+}
+
+func (g *Game) Setup() {
+	// load texture and ply mesh
+	err := goga.LoadResFromFolder(assets_dir)
+
+	if err != nil {
+		panic(err)
+	}
+
+	// create model
+	tex, err := goga.GetTex("cube.png")
+
+	if err != nil {
+		panic(err)
+	}
+
+	ply, err := goga.GetPly("cube.ply")
+
+	if err != nil {
+		panic(err)
+	}
+
+	mesh := goga.NewMesh(ply.IndexBuffer, ply.VertexBuffer, ply.TexCoordBuffer)
+
+	model := goga.NewModel(mesh, tex)
+	renderer, ok := goga.GetSystemByName("modelRenderer").(*goga.ModelRenderer)
+
+	if !ok {
+		panic("Could not find renderer")
+	}
+
+	renderer.Prepare(model)
+	renderer.Add(model.Actor, model.Pos3D, model.Tex, model.Mesh)
+	g.model = model
+
+	// enable depth test and buffer
+	goga.EnableDepthTest(true)
+	goga.ClearDepthBuffer(true)
+}
+
+func (g *Game) Update(delta float64) {
+	// update rotation on each frame around upper axis
+	g.model.Rot.Z += delta * 45
+}
+
+func main() {
+	game := Game{}
+	options := goga.RunOptions{ClearColor: goga.Vec4{1, 1, 1, 0},
+		Resizable:           true,
+		SetViewportOnResize: true,
+		ExitOnClose:         true}
+	goga.Run(&game, &options)
+}

game.go

@@ -392,6 +392,15 @@ func EnableAlphaBlending(enable bool) {
 	}
 }
 
+// Enables/Disables depth test.
+func EnableDepthTest(enable bool) {
+	if enable {
+		gl.Enable(gl.DEPTH_TEST)
+	} else {
+		gl.Disable(gl.DEPTH_TEST)
+	}
+}
+
 // Sets GL viewport and updates default resources and systems.
 func SetViewport(x, y, width, height int32) {
 	viewportWidth = int(width)