[Interest] Qt3D Framegraphs
Andy
asmaloney at gmail.com
Mon Sep 3 14:54:18 CEST 2018
Progress! Here's my current framegraph:
RenderSurfaceSelector:
Viewport:
ClearBuffers:
buffers: ColorDepthBuffer
clearColor: "#EEfaebd7"
NoDraw: {}
FrustumCulling:
# OnScreen
CameraSelector:
objectName: onScreenCameraSelector
RenderCapture:
objectName: onScreenCapture
# OffScreen
CameraSelector:
objectName: offScreenCameraSelector
RenderTargetSelector:
target:
RenderTarget:
attachments:
- RenderTargetOutput:
attachmentPoint: Color0
texture:
Texture2D:
width: 512
height: 512
format: RGBAFormat
ClearBuffers:
buffers: ColorDepthBuffer
clearColor: "#EEfaebd7"
NoDraw: {}
RenderCapture:
objectName: offScreenCapture
Results of the render captures:
onScreenCapture: https://postimg.cc/image/v26nfj36l/
offScreenCapture: https://postimg.cc/image/68x3evrvx/
I fixed the offscreen aspect ratio issue by creating a new offscreen camera
and forwarding all but these two signals:
Qt3DRender::QCamera::aspectRatioChanged
Qt3DRender::QCamera::projectionMatrixChanged
Question:
1) I am using an RGBAFormat for my texture. I changed the alpha in the
clear colour from 0x80 to 0xEE and I now see an alpha cleared background in
the offscreen (see image). I can just use RGB for my purposes right now,
but I'm curious why the onscreen clearing is not using the alpha channel? I
can confirm this by changing the clear colour to #FF000000 - I just get
solid black.
Problem:
1) The resulting scene isn't the same in the offscreen capture:
- the yellow cube is on top of everything
- the red & blue arrows aren't clipped by the plane
- it isn't antialiased
I'm wondering if this is because the shaders aren't being used for the
offscreen texture? I noticed in apitrace that when switching
GL_DRAW_FRAMEBUFFER to 0 (onscreen), glUseProgram(1) is called. This is not
called when switching GL_DRAW_FRAMEBUFFER to 1 (offscreen). Is the program
supposed to persist or does it need to be called again when switching
framebuffers?
(apitrace is super-cool. Thanks for the pointer.)
Thank you for your time & help!
---
Andy Maloney // https://asmaloney.com
twitter ~ @asmaloney <https://twitter.com/asmaloney>
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