Extending pre-pass renderer to support custom render targets

Feature requests
,
1

I want to extend babylon’s pre-renderer to support some custom render-target(s).
An example could be a id map rtt inspired by the one used in gpu-picking.
Sample: https://playground.babylonjs.com/#3W87R0#2

I found a way of integrating this by modifying the default.fragment.fx in packages/dev/core/src/Shaders/default.fragment.fx and including a block which writes to a separate rtt

	#ifdef PREPASS_IDMAP
		gl_FragData[PREPASS_IDMAP_INDEX] = vec4(1.0, 0.0, 0.0, writeGeometryInfo);
	#endif

I had to also add the textureFormat I wanted in the prepassRenderer, along with some other minor updates to fix all references.

  {
            purpose: Constants.PREPASS_IDMAP_TEXTURE_TYPE,
            type: Constants.TEXTURETYPE_UNSIGNED_BYTE,
            format: Constants.TEXTUREFORMAT_RGBA,
            name: "prePass_IdMap",
 }

I wanted to know if there is a simpler way of adding such a render target to the existing prePassRenderer ?

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2

This might be the kind of thing that is addressed by the new Frame Graph system, but maybe @Evgeni_Popov can comment when he is back.

1 Like
3

Yes, that’s something we will want to support with frame graphs and not with the prepass renderer, as the latter is more limited. At the time, it’s not possible to do it in a simple way, though. I’ve added it to the frame graph todo list.

4 Likes
4

awesome! looking forward to it!

1 Like