Add Skybox Example (#5)

* added skybox example

* use existing resource directory

examples/models/models_skybox.py

@@ -0,0 +1,67 @@
+from raylib.dynamic import raylib as rl, ffi
+from raylib.colors import *
+
+screenWidth = 1260
+screenHeight = 768
+
+rl.InitWindow(screenWidth, screenHeight, b'Skymap Demo')
+
+camera = ffi.new('struct Camera3D *', [[1, 1, 1], [4, 1, 4], [0, 1, 0], 70, 0])
+
+cube = rl.GenMeshCube(100, 100, 100)
+skybox = rl.LoadModelFromMesh(cube)
+
+skybox.materials[0].shader = rl.LoadShader(
+	b'resources/shaders/skybox.vs',
+	b'resources/shaders/skybox.fs'
+)
+
+rl.SetShaderValue(
+	skybox.materials[0].shader,
+	rl.GetShaderLocation(skybox.materials[0].shader, b"environmentMap"),
+	ffi.new('int[]', [rl.MAP_CUBEMAP]),
+	rl.UNIFORM_INT
+)
+
+shdrCubemap = rl.LoadShader(
+	b'resources/shaders/cubemap.vs',
+	b'resources/shaders/cubemap.fs'
+)
+
+rl.SetShaderValue(
+	shdrCubemap,
+	rl.GetShaderLocation(shdrCubemap, b'equirectangularMap'),
+	ffi.new('int[]', [0]),
+	rl.UNIFORM_INT
+)
+
+texHDR = rl.LoadTexture(b'resources/dresden_square.hdr')
+
+skybox.materials[0].maps[rl.MAP_CUBEMAP].texture = rl.GenTextureCubemap(shdrCubemap, texHDR, 512);
+
+rl.UnloadTexture(texHDR)
+rl.UnloadShader(shdrCubemap)
+
+rl.SetCameraMode(camera[0], rl.CAMERA_FIRST_PERSON)
+
+rl.SetTargetFPS(60)
+
+while not rl.WindowShouldClose():
+	rl.UpdateCamera(camera)
+	rl.BeginDrawing()
+	rl.ClearBackground(RAYWHITE)
+	rl.BeginMode3D(camera[0])
+	rl.DrawModel(skybox, [0, 0, 0], 1.0, WHITE)
+	rl.DrawGrid(10, 1.0)
+	for x in range(10):
+		for y in range(10):
+			rl.DrawCube([x * 2, 0, y * 2], 1, 1, 1, MAROON)
+			rl.DrawCubeWires([x * 2, 0, y * 2], 1, 1, 1, RED)
+	rl.EndMode3D()
+	rl.DrawFPS(10, 10)
+	rl.EndDrawing()
+
+rl.CloseWindow()
+rl.UnloadShader(skybox.materials[0].shader)
+rl.UnloadTexture(skybox.materials[0].maps[rl.MAP_CUBEMAP].texture)
+rl.UnloadModel(skybox)