After a couple of experiments with variable blur filters, I tried
a more interesting, and who knows... original approach. :)
First watch results here:
http://www.blender.org/bf/rt0001_0030.avihttp://www.blender.org/bf/hand0001_0060.avi
These are the steps in producing such results:
- In preprocess, the speed vectors to previous and next frame are
calculated. Speed vectors are screen-aligned and in pixel size.
- while rendering, these vectors get calculated per sample, and
accumulated in the vector buffer checking for "minimum speed".
(on start the vector buffer is initialized on max speed).
- After render:
- The entire image, all pixels, then is converted to quad polygons.
- Also the z value of the pixels is assigned to the polygons
- The vertices for the quads use averaged speed vectors (of the 4
corner faces), using a 'minimum but non-zero' speed rule.
This minimal speed trick works very well to prevent 'tearing' apart
when multiple faces move in different directions in a pixel, or to
be able to separate moving pixels clearly from non-moving ones
- So, now we have a sort of 'mask' of quad polygons. The previous steps
guaranteed that this mask doesn't have antialias color info, and has
speed vectors that ensure individual parts to move nicely without
tearing effects. The Z allows multiple layers of moving masks.
- Then, in temporal buffer, faces get tagged if they move or not
- These tags then go to an anti-alias routine, which assigns alpha
values to edge faces, based on the method we used in past to antialias
bitmaps (still in our code, check the antialias.c in imbuf!)
- finally, the tag buffer is used to tag which z values of the original
image have to be included (to allow blur go behind stuff).
- OK, now we're ready for accumulating! In a loop, all faces then get
drawn (with zbuffer) with increasing influence of their speed vectors.
The resulting image then is accumulated on top of the original with a
decreasing weighting value.
It sounds all quite complex... but the speed is still encouraging. Above
images have 64 mblur steps, which takes about 1-3 seconds per frame.
Usage notes:
- Make sure the render-layer has passes 'Vector' and 'Z' on.
- add in Compositor the VectorBlur node, and connect the image, Z and
speed to the inputs.
- The node allows to set amount of steps (10 steps = 10 forward, 10 back).
and to set a maximum speed in pixels... to prevent extreme moving things
to blur too wide.
- Live scanline updates while rendering
Using a timer system, each second now the tiles that are being processed
are checked if they could use display.
To make this work pretty, I had to use the threaded 'tile processor' for
a single thread too, but that's now proven to be stable.
Also note that these updates draw per layer, including ztransp progress
separately from solid render.
- Recode of ztransp OSA
Until now (since blender 1.0) the ztransp part was fully rendered and
added on top of the solid part with alpha-over. This adding was done before
the solid part applied sub-pixel sample filtering, causing the ztransp
layer to be always too blurry.
Now the ztransp layer uses same sub=pixel filter, resulting in the same
AA level (and filter results) as the solid part. Quite noticable with hair
renders.
- Vector buffer support & preliminary vector-blur Node
Using the "Render Layer" panel "Vector" pass button, the motion vectors
per pixel are calculated and stored. Accessible via the Compositor.
The vector-blur node is horrible btw! It just uses the length of the
vector to apply a filter like with current (z)blur. I'm committing it anyway,
I'll experiment with it further, and who knows some surprise code shows up!
A full detailed description of this will be done later... is several days
of work. Here's a summary:
Render:
- Full cleanup of render code, removing *all* globals and bad level calls
all over blender. Render module is now not called abusive anymore
- API-fied calls to rendering
- Full recode of internal render pipeline. Is now rendering tiles by
default, prepared for much smarter 'bucket' render later.
- Each thread now can render a full part
- Renders were tested with 4 threads, goes fine, apart from some lookup
tables in softshadow and AO still
- Rendering is prepared to do multiple layers and passes
- No single 32 bits trick in render code anymore, all 100% floats now.
Writing images/movies
- moved writing images to blender kernel (bye bye 'schrijfplaatje'!)
- made a new Movie handle system, also in kernel. This will enable much
easier use of movies in Blender
PreviewRender:
- Using new render API, previewrender (in buttons) now uses regular render
code to generate images.
- new datafile 'preview.blend.c' has the preview scenes in it
- previews get rendered in exact displayed size (1 pixel = 1 pixel)
3D Preview render
- new; press Pkey in 3d window, for a panel that continuously renders
(pkey is for games, i know... but we dont do that in orange now!)
- this render works nearly identical to buttons-preview render, so it stops
rendering on any event (mouse, keyboard, etc)
- on moving/scaling the panel, the render code doesn't recreate all geometry
- same for shifting/panning view
- all other operations (now) regenerate the full render database still.
- this is WIP... but big fun, especially for simple scenes!
Compositor
- Using same node system as now in use for shaders, you can composit images
- works pretty straightforward... needs much more options/tools and integration
with rendering still
- is not threaded yet, nor is so smart to only recalculate changes... will be
done soon!
- the "Render Result" node will get all layers/passes as output sockets
- The "Output" node renders to a builtin image, which you can view in the Image
window. (yes, output nodes to render-result, and to files, is on the list!)
The Bad News
- "Unified Render" is removed. It might come back in some stage, but this
system should be built from scratch. I can't really understand this code...
I expect it is not much needed, especially with advanced layer/passes
control
- Panorama render, Field render, Motion blur, is not coded yet... (I had to
recode every single feature in render, so...!)
- Lens Flare is also not back... needs total revision, might become composit
effect though (using zbuffer for visibility)
- Part render is gone! (well, thats obvious, its default now).
- The render window is only restored with limited functionality... I am going
to check first the option to render to a Image window, so Blender can become
a true single-window application. :)
For example, the 'Spare render buffer' (jkey) doesnt work.
- Render with border, now default creates a smaller image
- No zbuffers are written yet... on the todo!
- Scons files and MSVC will need work to get compiling again
OK... thats what I can quickly recall. Now go compiling!
