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Silverdust
Silverdust
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EDIT: Just found the solution by further examining the API: Adding Params.RenderTargetUsage = RenderTargetUsage.PreserveContents; into the PresentationParameter structure solves the problem.

It looks to me that the content of the backbuffer is - like with render targets being destroyed whenever you switch to another render target.

EDIT: Just found the solution by further examining the API: Adding Params.RenderTargetUsage = RenderTargetUsage.PreserveContents; into the PresentationParameter structure solves the problem.

It looks to me that the content of the backbuffer is - like with render targets being destroyed whenever you switch to another render target.

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Silverdust
Silverdust
  • 156
  • 4

Having the exactly same issue here - the following code snipped works perfectly fine:

private void DoRenderSkybox (GameTime Time) {
  this.Device.SetRenderTarget(this.GridTexture);
  this.Device.SetRenderTarget(null);


  // compute a temporary transformation matrix containing
  // the combined world and projection transfromation
  Matrix WorldViewProjection = this.Camera.View * this.Camera.Projection;

  // set the render target to the back buffer in any case
  this.Device.SetRenderTarget(null);

  // assign the vertex - declaration and the vertex- and the index - buffer
  this.Device.SetVertexBuffer(this.SkyboxVertices);
  this.Device.Indices = this.SkyboxIndices;

  // choose the appropriate technique for the current render pass
  this.SceneEffect.CurrentTechnique = SceneEffect.Techniques["Skybox"];
  this.SceneEffect.CurrentTechnique.Passes[0].Apply();
  this.SceneEffect.Parameters["WorldViewProjection"].SetValue(WorldViewProjection);

  // finally render the sykbox with disabled depth stencil buffering
  this.Device.DepthStencilState = DepthStencilState.None;
  this.Device.DrawIndexedPrimitives( PrimitiveType.TriangleList, 0, 0, 36, 0, 12);
  this.Device.DepthStencilState = DepthStencilState.Default;


  //this.Device.SetRenderTarget(this.GridTexture);
  //this.Device.SetRenderTarget(null);
}

However, if I assign (and right away unassign) the render target at the end of the function like so:

    private void DoRenderSkybox (GameTime Time) {
  //this.Device.SetRenderTarget(this.GridTexture);
  //this.Device.SetRenderTarget(null);
  
  
  // compute a temporary transformation matrix containing
  // the combined world and projection transfromation
  Matrix WorldViewProjection = this.Camera.View * this.Camera.Projection;

  // set the render target to the back buffer in any case
  this.Device.SetRenderTarget(null);
  this.Device.Clear(Color.Black);

  // assign the vertex - declaration and the vertex- and the index - buffer
  this.Device.SetVertexBuffer(this.SkyboxVertices);
  this.Device.Indices = this.SkyboxIndices;
  
  // choose the appropriate technique for the current render pass
  this.SceneEffect.CurrentTechnique = SceneEffect.Techniques["Skybox"];
  this.SceneEffect.CurrentTechnique.Passes[0].Apply();
  this.SceneEffect.Parameters["WorldViewProjection"].SetValue(WorldViewProjection);

  // finally render the sykbox with disabled depth stencil buffering
  this.Device.DepthStencilState = DepthStencilState.None;
  this.Device.DrawIndexedPrimitives( PrimitiveType.TriangleList, 0, 0, 36, 0, 12);
  this.Device.DepthStencilState = DepthStencilState.Default;


  this.Device.SetRenderTarget(this.GridTexture);
  this.Device.SetRenderTarget(null);
}

nothing is being rendered - I got a purple screen! Does that make any sense to you!

P.S. I know the sample doesn't make much sense (like assigning and right away unassigning a render target). The real scenario here is much more complicated but I was able to narrow down the essence of the problem to this strange behaviour, which I can demonstrate in this very simple example!