This fixes an issue which darkened the render from inside a
volume with sky or premul on. Still need to find a good way to
get an alpha value back into the shader (for compositing etc)
without getting the render distorted by premul.
Replaced 'Sharp' falloff with 'Soft'. This falloff type has
a variable softness, and can get some quite smooth results.
It can be useful to get smooth transitions in density when
you're using particles on a large scale:
http://mke3.net/blender/devel/rendering/volumetrics/pd_falloff_soft.jpg
Also removed 'angular velocity' turbulence source - it
wasn't doing anything useful atm
This was a bit complicated to do, but is working pretty well now, and can make shading significantly faster to render.
This option pre-calculates self-shading information into a
3d voxel grid before rendering, then uses and interpolates
that data during the main rendering phase, rather than
calculating shading for each sample. It's an approximation
and isn't as accurate as getting the lighting directly,
but in many cases it looks very similar and renders much faster.
The voxel grid covers the object's 3D screen-aligned bounding box
so this may not be that useful for large volume regions like a
big range of cloud cover, since you'll need a lot of resolution.
The render time speaks for itself here:
http://mke3.net/blender/devel/rendering/volumetrics/vol_light_cache_interpolation.jpg
The resolution is set in the volume panel - it's the resolution
of one edge of the voxel grid. Keep in mind that the higher the
resolution, the more memory needed, like in fluid sim. The
memory requirements increase with the cube of the edge
resolution so be careful. I might try and add a little memory
calculator thing like fluid sim has there later.
The voxels are interpolated using trilinear interpolation -
here's a comparison image I made during testing:
http://mke3.net/blender/devel/rendering/volumetrics/vol_light_cache_compare.jpg
There might still be a couple of little tweaks I can do to
improve the visual quality, I'll see.
Particle system crashed in convertblender, missing NULL check.
This fixes crash, render survives, but I doubt it was meant so...
Will leave it Janne to evaluate later.
regression files, it showed small dark outline errors on envmap.
This commit rewinds bugfix #8437, which actually had to be fixed on
another location in code, which was done a few weeks ago. :)
Index OB pass didn't support FSA for Ztransp.
Also made buttons to set black/white for non-RGBA images hide in Image Window,
the Curves color code only supports 4 channels atm.
This is on by default, and trades random noise for banding. It jitters
the step size from 75% to 125% of its original amount, and since it
uses the threaded random seeds, shouldn't flicker during animation.
These two images took roughly the same time to render:
http://mke3.net/blender/devel/rendering/volumetrics/vol_stepsize_randomized.jpg
- modified point density so that it returns a more consistent
density with regards to search radius. Previously larger radii
would give much higher density but this is equalised out now.
- Added a new volume material option 'density scale'. This is an
overall scale multiplier for density, allowing you to (for
example) crank down the density to a more desirable range if
you're working at a large physical scale. Volume rendering is
fundamentally scale dependant so this lets you correct to get the
right visual result.
- Also tweaked a few constants, old files won't render exactly
the same, just minor things though.
proper results, should bake as if SSS was disabled.
- Fix for GLSL to handle failing shadow buffer creation better.
- Fix for sky/atmosphere version patch, was not doing files from 2.46
and newer.
due to jittering of the start position for antialiasing in a pixel.
Now it distributes the start position over the fixed osa sample
positions, instead of of random positions in space. The ugly bit is
that a custom ordering was defined for osa 8/11/16 to ensure that the
first 4 are distributed relatively fair for adaptive sampling to decide
if more samples need to be taken.
This addition allows you to perturb the point density with noise, to give
the impression of more resolution. It's a quick way to add detail, without
having to use large, complex, and slower to render particle systems.
Rather than just overlaying noise, like you might do by adding a secondary
clouds texture, it uses noise to perturb the actual coordinate looked up
in the density evaluation. This gives a much better looking result, as it
actually alters the original density.
Comparison of the particle cloud render without, and with added turbulence
(the render with turbulence only renders slightly more slowly):
http://mke3.net/blender/devel/rendering/volumetrics/pd_turbulence.jpg
Using the same constant noise function/spatial coordinates will give a
static appearance. This is fine (and quicker) if the particles aren't
moving, but on animated particle systems, it looks bad, as if the
particles are moving through a static noise field. To overcome this, there
are additional options for particle systems, to influence the turbulence
with the particles' average velocity, or average angular velocity. This
information is only available for particle systems at the present.
Here you can see the (dramatic) difference between no turbulence, static
turbulence, and turbulence influenced by particle velocity:
http://mke3.net/blender/devel/rendering/volumetrics/turbu_compare.mov
- the number of segments was always 1 too many on cyclic curves.
- [#17739] - normals were not being calculated when rendering curves.
Replaced macro DL_SURFINDEX with a function. it that assumes variable names and could break from the loop that called it.
Otherwise known as a phase function, this determines in which directions
the light is scattered in the volume. Until now it's been isotropic
scattering, meaning that the light gets scattered equally in all
directions. This adds some new types for anisotropic scattering, to
scatter light more forwards or backwards towards the viewing direction,
which can be more similar to how light is scattered by particles in nature.
Here's a diagram of how light is scattered isotropically and anisotropically:
http://mke3.net/blender/devel/rendering/volumetrics/phase_diagram.png
The new additions are:
- Rayleigh
describes scattering by very small particles in the atmosphere.
- Mie Hazy / Mie Murky
more generalised, describes scattering from large particle sizes.
- Henyey-Greenstein
a very flexible formula, that can be used to simulate a wide range of
scattering. It uses an additional 'Asymmetry' slider, ranging from -1.0
(backward scattering) to 1.0 (forward scattering) to control the
direction of scattering.
- Schlick
an approximation of Henyey-Greenstein, working similarly but faster.
And a description of how they look visually (just an omnidirectional lamp
inside a volume box)
http://mke3.net/blender/devel/rendering/volumetrics/phasefunctions.jpg
* Sun/sky integration
Volumes now correctly render in front of the new physical sky. Atmosphere
still doesn't work correctly with volumes, due to something that i hope
can be fixed in the atmosphere rendering, but the sky looks quite good.
http://mke3.net/blender/devel/rendering/volumetrics/sky_clouds.png
This also works very nicely with the anisotropic scattering, giving
clouds their signature bright halos when the sun is behind them:
http://mke3.net/blender/devel/rendering/volumetrics/phase_cloud.mov
in comparison here's a render with isotropic scattering:
http://mke3.net/blender/devel/rendering/volumetrics/phase_cloud_isotropic.png
* Added back the max volume depth tracing limit, as a hard coded value -
fixes crashes with weird geometry, like the overlapping faces around
suzanne's eyes. As a general note, it's always best to use volume
materials on airtight geometry, without intersecting or overlapping faces.
the emission component by the density at the current point, which
made the volume too bright in less dense areas. This made it look
too rough, as opposed to smooth as it should be. This makes the
particle rendering look *much* better, thanks a bunch to ZanQdo for
complaining and kicking my butt to make me realise the error.
Here's an example of how smooth it looks now:
http://mke3.net/blender/devel/rendering/volumetrics/smoke_test03.movhttp://mke3.net/blender/devel/rendering/volumetrics/smoke_test03.blend
Settings in existing files will have to be tweaked a bit, since
what they were set up for before, was incorrect.
* Added two new interpolation types to Point Density: Constant and
Root. These work similarly to in proportional edit for example,
just gives a bit more choice over how hard-edged the particles
should look.
Replaced the previous KD-tree (for caching points) with a
BVH-tree (thanks to Andre 'jaguarandi' Pinto for help here!).
The bvh is quite a bit faster and doesn't suffer some of the
artifacts that were apparent with the kd-tree.
I've also added a choice of falloff types: Standard, Smooth, and
Sharp. Standard gives a harder edge, easier to see individual
particles, and when used with a larger radius, Smooth and Sharp
falloffs make a much cloudier appearance possible. See the image
below (note the settings and render times too)
http://mke3.net/blender/devel/rendering/volumetrics/pointdensity_bvh.jpg
limit ray intersections like as for ray transparency). It
remains to be seen if it's even that useful, and was
preventing refracting materials behind volumes from
working easily.
SunSky didn't include skycolor in raytrace.
Note: there seems to be an error in sunsky when looking straight down,
so this option requires raytracing stuff not in outer space. :)
* subsurf code had a lot of unused variables, removed these where they are obviously not needed. commented if they could be useful later.
* some variables declorations hide existing variables (many of these left), but fixed some that could cause confusion.
* removed unused vars
* obscure python memory leak with colorband.
* make_sample_tables had a loop running wasnt used.
* if 0'd functions in arithb.c that are not used yet.
* made many functions static
- removed ugly clamping function (it was dividing XYZ based on max of
one of the values)
- added option to use Exposure, this only works for brightness (Y).
results look very pleasant, foggy and hazy results are possible.
with exposre==0, no exposure happens for HDR extreme range skies,
this is how yafray rendered it.
- added menu for choosing color spaces (CIE = modern lcds)
Please review! (and yes i know it's still not in World :)
The Point Density texture now has some additional options for how
the point locations are cached. Previously it was all relative to
worldspace, but there are now some other options that make things
a lot more convenient for mapping the texture to Local (or Orco).
Thanks to theeth for helping with the space conversions!
The new Object space options allow this sort of thing to be possible
- a particle system, instanced on a transformed renderable object:
http://mke3.net/blender/devel/rendering/volumetrics/pd_objectspace.mov
It's also a lot easier to use multiple instances, just duplicate
the renderable objects and move them around.
The new particle cache options are:
* Emit Object space
This caches the particles relative to the emitter object's
coordinate space (i.e. relative to the emitter's object center).
This makes it possible to map the Texture to Local or Orco
easily, so you can easily move, rotate or scale the rendering
object that has the Point Density texture. It's relative to the
emitter's location, rotation and scale, so if the object you're
rendering the texture on is aligned differently to the emitter,
the results will be rotated etc.
* Emit Object Location
This offsets the particles to the emitter object's location in 3D
space. It's similar to Emit Object Space, however the emitter
object's rotation and scale are ignored. This is probably the
easiest to use, since you don't need to worry about the rotation
and scale of the emitter object (just the rendered object), so
it's the default.
* Global Space
This is the same as previously, the particles are cached in global space, so to use this effectively you'll need to map the texture to Global, and have the rendered object in the right global location.
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!
