Removed all the old particle rendering code and options I had in there
before, in order to make way for...
A new procedural texture: 'Point Density'
Point Density is a 3d texture that find the density of a group of 'points'
in space and returns that in the texture as an intensity value. Right now,
its at an early stage and it's only enabled for particles, but it would be
cool to extend it later for things like object vertices, or point cache
files from disk - i.e. to import point cloud data into Blender for
rendering volumetrically.
Currently there are just options for an Object and its particle system
number, this is the particle system that will get cached before rendering,
and then used for the texture's density estimation.
It works totally consistent with as any other procedural texture, so
previously where I've mapped a clouds texture to volume density to make
some of those test renders, now I just map a point density texture to
volume density.
Here's a version of the same particle smoke test file from before, updated
to use the point density texture instead:
http://mke3.net/blender/devel/rendering/volumetrics/smoke_test02.blend
There are a few cool things about implementing this as a texture:
- The one texture (and cache) can be instanced across many different
materials:
http://mke3.net/blender/devel/rendering/volumetrics/pointdensity_instanced.png
This means you can calculate and bake one particle system, but render it
multiple times across the scene, with different material settings, at no
extra memory cost.
Right now, the particles are cached in world space, so you have to map it
globally, and if you want it offset, you have to do it in the material (as
in the file above). I plan to add an option to bake in local space, so you
can just map the texture to local and it just works.
- It also works for solid surfaces too, it just gets the density at that
particular point on the surface, eg:
http://mke3.net/blender/devel/rendering/volumetrics/pointdensity_solid.mov
- You can map it to whatever you want, not only density but the various
emissions and colours as well. I'd like to investigate using the other
outputs in the texture too (like the RGB or normal outputs), perhaps with
options to colour by particle age, generating normals for making particle
'dents' in a surface, whatever!
Initial commit for supporting rendering particles directly as
volume density. It works by looking up how many particles are
within a specified radius of the currently shaded point and using
that to calculate density (which is used just as any other
measure of density would be).
http://mke3.net/blender/devel/rendering/volumetrics/smoke_test01.mov
http://mke3.net/blender/devel/rendering/volumetrics/smoke_test01.blend
Right now it's an early implementation, just to see that it can
work - it may end up changing quite a bit. Currently, it's just a
single switch on the volume material - it looks up all particles
in the scene for density at the current shaded point in world
space (so the volume region must enclose the particles in order
to render them.
This will probably change - one idea I have is to make the
particle density estimation a procedural texture with options for:
* the object and particle system to use
* the origin of the co-ordinate system, i.e. object center, world
space, etc.
This would allow you in a sense, to instance particle systems for
render - you only need to bake one particle system, but you can
render it anywhere.
Anyway, plenty of work to do here, firstly on getting a nice
density evaluation with falloff etc...
* Now it's possible to render with the camera inside a volume. I'm not sure how this goes with overlapping volumes yet, will look at it. But it allows nice things like this :)
http://mke3.net/blender/devel/rendering/volumetrics/clouds_sky.mov
* Sped up shading significantly by not doing any shading if the density
of the current sample is less than 0.01 (there's nothing to shade there anyway!) Speeds up around 200% on that clouds scene.
* Fixed a bug in global texture coordinates for volume textures
Now other objects (and sky) correctly render if they're partially
inside or behind a volume. Previously all other objects were ignored,
and volumes just rendered on black. The colour of surfaces inside or
behind the volume gets correctly attenuated by the density of the
volume in between - i.e. thicker volumes will block the light coming
from behind. However, other solid objects don't receive volume shadows
yet, this is to be worked on later.
http://mke3.net/blender/devel/rendering/volumetrics/vol_inside_behind.png
Currently this uses raytracing to find intersections within the volume,
and rays are also traced from the volume, heading behind into the
scene, to see what's behind it (similar effect to ray transp with IOR
1). Because of this, objects inside or behind the volume will not be
antialiased. Perhaps I can come up with a solution for this, but until
then, for antialiasing, you can turn on Full OSA (warning, this will
incur a slowdown). Of course you can always avoid this by rendering
volumes on a separate renderlayer, and compositing in post, too.
Another idea I've started thinking about is to calculate an alpha
value, then use ztransp to overlay on top of other objects. This won't
accurately attenuate and absorb light coming from objects behind the
volume, but for some situations it may be fine, and faster too.
Rather than a single absorption value to control how much light is absorbed as it
travels through a volume, there's now an additional absorption colour. This is
used to absorb different R/G/B components of light at different amounts. For
example, if a white light shines on a volume which absorbs green and blue
components, the volume will appear red.
To make it easier to use, the colour set in the UI is actually the inverse of the
absorption colour, so the colour you set is the colour that the volume will
appear as.
Here's an example of how it works:
http://mke3.net/blender/devel/rendering/volumetrics/vol_col_absorption.jpg
And this can be textured too:
http://mke3.net/blender/devel/rendering/volumetrics/vol_absorb_textured.png
Keep in mind, this doesn't use accurate spectral light wavelength mixing (just
R/G/B channels) so in cases where the absorption colour is fully red green or
blue, you'll get non-physical results.
Todo: refactor the volume texturing internal interface...
This is an initial commit to get it in SVN and make it easier to work on.
Don't expect it to work perfectly, it's still in development and there's
plenty of work still needing to be done. And so no I'm not very interested
in hearing bug reports or feature requests at this stage :)
There's some info on this, and a todo list at:
http://mke3.net/weblog/volume-rendering/
Right now I'm trying to focus on getting shading working correctly (there's
currently a problem in which 'surfaces' of the volume facing towards or away
from light sources are getting shaded differently to how they should be),
then I'll work on integration issues, like taking materials behind the volume
into account, blending with alpha, etc. You can do simple testing though,
mapping textures to density or emission on a cube with volume material.
- Added blending mode and factor option, so it's more clear and
controllable what happens with it. Also nice for crazy effects
of course!
- Preview render now shows preview for it too
On the todos:
- have this in World buttons (as well) for quicker sky setups
- review math of color clamping and scaling, this is definitely
not good... but a fix will make old files look very different.
Finally, after a long time new render candy for the non-game peoples! :)
Good doc is here: (url splits in two)
http://www.harkyman.com/2008/08/06/controllable-shadow-intensity-
and-color/
Note the colorpicker for shadow is in "Shadow and Spot" panel. A bit
hidden, could get more attention. For later. :)
the features that are needed to run the game. Compile tested with
scons, make, but not cmake, that seems to have an issue not related
to these changes. The changes include:
* GLSL support in the viewport and game engine, enable in the game
menu in textured draw mode.
* Synced and merged part of the duplicated blender and gameengine/
gameplayer drawing code.
* Further refactoring of game engine drawing code, especially mesh
storage changed a lot.
* Optimizations in game engine armatures to avoid recomputations.
* A python function to get the framerate estimate in game.
* An option take object color into account in materials.
* An option to restrict shadow casters to a lamp's layers.
* Increase from 10 to 18 texture slots for materials, lamps, word.
An extra texture slot shows up once the last slot is used.
* Memory limit for undo, not enabled by default yet because it
needs the .B.blend to be changed.
* Multiple undo for image painting.
* An offset for dupligroups, so not all objects in a group have to
be at the origin.
Baking would split non-planer quads in an unpredictable way, which is fine for rending but game engines often use a fixed order (0,1,2), (0,2,3) or (1,2,3) (1,3,0).
Added an option to use a fixed order when baking.
computers, probably due to slow multithreaded malloc. Now each render
thread keeps a list of qmc samplers that it fills as needed while
rendering (since it is hard to predict the actual amount needed in
advance due to ray recursion).
Fix for bug #7418: texture ipo's didn't show for textures in node materials.
Fix for part of bug #6758: node materials in other node materials could
miss texture coordinates.
but only when the UV's are connected. That fixes some artifacts when
baking and using tangent space normal maps. It does mean increased
memory usage because it now stores 4 tangents per face like UV's,
and increased processing time, but there's no simple way around that.
the renderer could lead to results being reused for unrelated
points, result was one wrong pixel or strand per part. Now instead
of setting the sample counter to 0 multiple times, it keeps a global
counter per thread for the whole render.
coordinates from the object as if they were in their original position,
untransformed by dupligroups or dupliverts. Otherwise the textures of
such objects would change depending on their position.
This adds a few settings to control global render quality, for faster
renders when tweaking lighting etc. The implementation is not so great,
and this should really be part of a proper render profile and preset
system. So for now it's a hidden Peach feature, enabled by setting rt
to 1. Before the next release, I'll either remove or improve it.
Settings are:
- Maximum subsurf level
- Child particles percentage
- Maximum shadow map samples
- AO and SSS quality factor
images. Found method that doesn't require image to be rendered larger.
Note: assembling pre-rendered parts that are result of FSA renders might
still give minor visible artefacts on edges; however, we should include
such render methods in the render pipeline, so multiple computers can
each render parts, save all samples, and have 1 computer assembling and
compositing all. This is for another project... :)
Now bounding boxes are computed per object, and checked first before
zbuffering objects. For strands, bounding boxes are computed per
original face in the mesh. Overall the speed improvement from this
is quite small (zbuffering is rarely the bottleneck), but it seems a
sensible thing to do anyway.
They now also store a list of samples per pixel, and then get
shaded together with the ztransp samples. This comes with a
slight speed hit, but mainly memory might be a concern. However,
testing some peach scenes I haven't problems.
This completes the pipeline make-over, as started in 2006. With this
option, during rendering, each sample for every layer and pass is being
saved on disk (looks like non-antialiased images). Then the composite
and color correction happens, then a clip to 0-1 range, and only in end
all samples get combined - using sampling filters such as gauss/mitch/catmul.
This results in artefact-free antialiased images. Even Z-combine or
ID masks now work perfect for it!
This is an unfinished commit btw; Brecht will finish this for strands.
Also Halo doesnt work yet.
To activate FSA: press "Save Buffers" and the new button next to it. :)
Problem: artist wants character to walk in grass, but still have all rendered
in seperate render-layers, for postpro effects and vblur. How to efficiently
create a mask image you can put *over* the character for the grass?
Solution has two parts; this commits allows any layer inside of the renderlayers
to become a Z-mask (Z values for solid gets filled in, but not rendered).
Second part of commit is render option "Only render stuff that's in front of
a zbuffer value that was filled in (saves render time)
of strands changing between frames, vector blur couldn't work. Now
speed vectors are interpolated from the surface. This also means
child particles don't have to be computed in the previous and next
frames, so saves time too.
Also, duplis are now taking into account, the proper way to exclude
them is to set the material to be not traceable.
Removed an unnecessary pointer from the VlakRen struct to save some
memory, not really that significant, but still, saves 70 mb for 10
million faces.
=============================
A new approximate ambient occlusion method has been added, next to the
existing one based on raytracing. This method is specifically targetted
at use in animations, since it is inherently noise free, and so will
not flicker across frames.
http://www.blender.org/development/current-projects/changes-since-244/approximate-ambient-occlusion/http://peach.blender.org/index.php/approximate-ambient-occlusion/
Further improvements are still needed, but it can be tested already. There
are still a number of known issues:
- Bias errors on backfaces.
- For performance, instanced object do not occlude currently.
- Sky textures don't work well, the derivatives for texture evaluation
are not correct.
- Multiple passes do not work entirely correct (they are not accurate
to begin with, but could be better).
Lampbuffers require painful bias tweaking (to prevent aliasing or to
get shadow detail). Sometimes you want this different per object, like
for gras you want less shadow detail, but for the ground you want high
detail. This feature allows to tweak it.
The new "LBias" slider is in shader panel, bottom. Ugly! But, thats for
later...
It seems everytime I try to fix something here I break something
else, but anyway, another try at getting this to work properly.
Fixes for:
- Getting dupliverts/faces derivedmesh with orco caused wrong results
on meshes in linked dupligroups with proxy, because modifier stack
was revaluated with wrong object matrix, now gets orco another way.
- Fix render instances being hidden when original object was not added
to the object render list.
- Changed the way object instances find their original objects, now
works the other way around, original objects look for their instances
instead.
There's probably issues still with recursive dupligroups..
====================
- "From Dupli" option for orco and uv texture coordinates. For dupliverts,
duplifaces and dupli particles, this uses the orco and uv at the point
on the parent surface. Can for example be used for texturing feathers
and leafs. Note that uv only works for duplifaces and particles emitted
from faces, these are not defined at vertices.
- "Width Fade" option for strand render, to fade out along the width of the
strand. Committing this so it can be tested, might be changed or removed
even, if it doesn't give nice results.
============================
- Strand render now has options to remove child strands as
the object's faces becomes smaller, in the Simplification
particle panel.
- "Reference Size" is the approximate size of the object on
screen, after which simplification starts.
- "Rate" is how fast strands are removed.
- "Transition" is the percentage of strands being faded out as
they are removed.
- Another "Viewport" option removes strands on faces that are
outside of the viewport. "Rate" again controls how fast these
are removed.
- Strand render in Blender Units now has an adjustable minimum
width. Below this minimum width, strands start fading out
instead of getting smaller.
===============================
- One shadowbuffer per thread.
- Added more break tests in shadow buffer code.
- Removed R.clipcrop global, solution is not nice yet, but at
least threadsafe.
- Fixed bug in strand render shadow buffer code.
=================
Big commit, but little user visible changes.
- Dupliverts and duplifaces are now rendered as instances, instead
of storing all of the geometry for each dupli, now an instance is
created with a matrix transform refering to the source object.
This should allow us to render tree leaves more memory efficient.
- Radiosity and to some degree raytracing of such objects is not
really efficient still. For radiosity this is fundamentally hard
to solve, but raytracing an octree could be created for each object,
but the current octree code with it's fixed size doesn't allow this
efficiently.
- The regression tests survived, but with I expect that some bugs will
pop up .. hopefully not too many :).
Implementation Notes
====================
- Dupligroups and linked meshes are not rendered as instances yet,
since they can in fact be different due to various reasons,
instancing of these types of duplis that are the same can be added
for them at a later point.
- Each ObjectRen now stores it's own database, instead of there being
one big databases of faces, verts, .. . Which objects that are actually
rendered are defined by the list of ObjectRenInstances, which all refer
to an ObjectRen.
- Homogeneous coordinatess and clipping is now not stored in vertices
anymore, but instead computed on the fly. This couldn't work for
instances. That does mean some extra computation has to be done, but
memory lookups can be slow too, and this saves some memory. Overall
I didn't find a significant speed impact.
- OSA rendering for solid and ztransp now is different. Instead of e.g.
going 8 times over the databases times and rendering the z-buffer, it
now goes over the database once and renders each polygon 8 times. That
was necessary to keep instances efficient, and can also give some
performance improvement without instances.
- There was already instancing support in the yafray export code, now it
uses Blender's render instances for export.
- UV and color layer storage in the render was a bit messy before, now
should be easier to understand.
- convertblender.c was reorganized somewhat. Regular render, speedvector
and baking now use a single function to create the database, previously
there was code duplicated for it.
- Some of these changes were done with future multithreading of scene
and shadow buffer creation in mind, though especially for scene creation
much work remains to be done to make it threadsafe, since it also involves
a lot of code from blenkernel, and there is an ugly conflict with the way
dupli groups work here .. though in the render code itself it's almost there.
=========
- Fix crash in particle transform with the particle system not editable.
- Particle child distribution and caching is now multithreaded.
- Child particles now have a separate Render Amount next to the existing
Amount. The render amount particles are now only distributed and cached
at render time, which should make editing with child particles faster.
- Two new options for diffuse strand shading:
- Surface Diffuse: computes the strand normal taking the normal at
the surface into account.
- Blending Distance: the distance in Blender units over which to
blend in the normal at the surface.
- Special strand rendering for more memory efficient and faster hair and
grass. This is a work in progress, and has a number of known issues,
don't report bugs to me for this feature yet.
More info:
http://www.blender.org/development/current-projects/changes-since-244/particles/
