I have been working through Riemers ShadowMap tutorial and everything was going well until the section on drawing to a separate rendertarget. I am using a different model and quads but I assumed the process would still work.
If I draw the scene directly to the back buffer I get: 
When I draw it first to a RenderTarget2D and THEN to the screen, I get this weird transparent effect only on the model, the textured primitives below are still rendered fine:
The RenderTarget is defined:
PresentationParameters pp = device.PresentationParameters; renderTarget = new RenderTarget2D(device, pp.BackBufferWidth, pp.BackBufferHeight, true, device.DisplayMode.Format, DepthFormat.Depth24); And it is used in this way:
protected override void Draw(GameTime gameTime) { device.SetRenderTarget(renderTarget); device.Clear(ClearOptions.Target | ClearOptions.DepthBuffer, Color.Black, 1.0f, 0); DrawScene("Simplest"); device.SetRenderTarget(null); shadowMap = (Texture2D)renderTarget; device.Clear(ClearOptions.Target | ClearOptions.DepthBuffer, Color.DarkSlateBlue, 1.0f, 0); using (SpriteBatch sb = new SpriteBatch(device)) { sb.Begin(); sb.Draw(shadowMap, new Vector2(0, 0), null, Color.White, 0, new Vector2(0, 0), 1.0f, SpriteEffects.None, 1); sb.End(); } base.Draw(gameTime); } What gives?
Edit 1: I resolved the transparency effect by resetting:
device.DepthStencilState = DepthStencilState.Default; device.BlendState = BlendState.Opaque; But now the model has a purple tint on the side away from the light. Something to do with my Shader code I presume.
Edit 2: Turns out the purple (blue) colour was a result of the window being cleared to .DarkSlateBlue and the RenderTarget having alpha transparency. Fixed with:
sb.Begin(SpriteSortMode.Immediate, BlendState.Opaque); 