hlsl: writing data to buffer in shader?

1

I want to access a buffer in pixel shader and write data to it( something like shader storage buffer object in opengl). Is there such buffer in directx? I havn’t used it before…thanks!:grinning:

3

i’m trying to implement a 2d shadow shader.
So I think I can firstly draw all sprites and record all pixels drawn.
Then
I draw a full screen quad with a function in pixel shader to judge if
this pixel is part of the shadow using the data recorded in the last
step. /though there is a problem of rendering sprites on top of their
shadows…/
Thus it needs a texture buffer to store those pixels drawn in the first step(in pixel shader), which maybe a large one…

4

use rendertarget?..

5

what you want is a rendertarget.

A rendertarget is simply a texture (or a buffer if you want to call it that).

For your 2D shadows the whole thing would look like this:

    private RenderTarget2D renderTarget;

//Initialize our code

    public void Initialize(GraphicsDevice graphicsDevice)
            {
                _graphicsDevice = graphicsDevice;
                width = graphicsDevice.PresentationParameters.BackBufferWidth;
                height = graphicsDevice.PresentationParameters.BackBufferHeight;
        //this is youc custom shader. I load it in another class, but you can do whatever
        _shadowEffect= Art.PostProcess;

        spriteBatch = new SpriteBatch(graphicsDevice);

        if (renderTarget != null)
        {
            renderTarget.Dispose();
        }
        renderTarget = new RenderTarget2D(graphicsDevice, width, height, false, SurfaceFormat.Color, DepthFormat.Depth24Stencil8);
    }

//

public void Draw(List<BasicEntity> entityList, Vector2 Camera)
{
    //Here we declare the texture which we will write our graphics stuff to
    _graphicsDevice.SetRenderTarget(renderTarget);

    _graphicsDevice.Clear(Color.DarkSlateGray);

   //Draw all our stuff which will have shadows!
    spriteBatch.Begin(SpriteSortMode.Deferred, null, SamplerState.PointWrap, null, null);


    //Draw Entities
    foreach (BasicEntity entity in entityList)
    {
        spriteBatch.Draw(entity.spriteTexture, entity.GetDestinationRectangle(Camera), entity.GetSourceRectangle(), entity.GetColor(), 0, Vector2.Zero, entity.GetOrientation(), 0);
    }

    spriteBatch.End();

    //Set the renderTarget to null -> draw directly to the backbuffer (to the final output!)
    _graphicsDevice.SetRenderTarget(null);

    //Background: draw your background below

   //...

     //Draw the shadows below
    spriteBatch.Begin(0, BlendState.Opaque, SamplerState.AnisotropicClamp, DepthStencilState.None, RasterizerState.CullNone, __shadowEffect);
    //Draw the renderTarget again in your shader where you process the shadows.
    //Basically everything we have drawn just agian in black and blurred and with an offset for example to create the shadow
    spriteBatch.Draw(renderTarget, new Rectangle(0, 0, _graphicsDevice.PresentationParameters.BackBufferWidth, _graphicsDevice.PresentationParameters.BackBufferHeight), Color.White);
    spriteBatch.End();

      //Draw the foreground below
      //we can redraw our original rendertarget here
      //by using spritebatch.begin .... draw(renderTarget) ... end

}
1 Like
6

oh, thanks very much! that’s exactly what I’m looking for:grin: