Implementation of the design task #142969.
This adds the following:
- Exact GPU interpolation of curves of all types.
- Radius attribute support.
- Cyclic curve support.
- Resolution attribute support.
- New Cylinder hair shape type.
What changed:
- EEVEE doesn't compute random normals for strand hairs anymore. These are considered legacy now.
- EEVEE now have an internal shadow bias to avoid self shadowing on hair.
- Workbench Curves Strip display option is no longer flat and has better shading.
- Legacy Hair particle system evaluates radius at control points before applying additional subdivision. This now matches Cycles.
- Color Attribute Node without a name do not fetch the active color attribute anymore. This now matches Cycles.
Notes:
- This is not 100% matching the CPU implementation for interpolation (see the epsilons in the tests).
- Legacy Hair Particle points is now stored in local space after interpolation.
The new cylinder shape allows for more correct hair shading in workbench and better intersection in EEVEE.
| | Strand | Strip | Cylinder |
| ---- | --- | --- | --- |
| Main |  |  | N/A |
| PR |  |  |  |
| | Strand | Strip | Cylinder |
| ---- | --- | --- | --- |
| Main |  | | N/A |
| PR | ||  |
Cyclic Curve, Mixed curve type, and proper radius support:
Test file for attribute lookup: [test_attribute_lookup.blend](/attachments/1d54dd06-379b-4480-a1c5-96adc1953f77)
Follow Up Tasks:
- Correct full tube segments orientation based on tangent and normal attributes
- Correct V resolution property per object
- More attribute type support (currently only color)
TODO:
- [x] Attribute Loading Changes
- [x] Generic Attributes
- [x] Length Attribute
- [x] Intercept Attribute
- [x] Original Coordinate Attribute
- [x] Cyclic Curves
- [x] Legacy Hair Particle conversion
- [x] Attribute Loading
- [x] Additional Subdivision
- [x] Move some function to generic headers (VertBuf, OffsetIndices)
- [x] Fix default UV/Color attribute assignment
Pull Request: https://projects.blender.org/blender/blender/pulls/143180
This does a few things:
- Add support for templated struct.
- Change parsing of template scope.
Now all template scope `<..>` are parsed properly.
- Rework to support better match syntax.
- Avoid warning from scope guard processing. Now initialize
the return value to zero.
Pull Request: https://projects.blender.org/blender/blender/pulls/145132
This adds the following features:
- `class` keyword support: checked by C++, mutated to struct for shader.
- `private` and `public` keywords: checked by C++, removed for shader.
- `static` methods.
- `const` and non-const methods.
What is not supported:
- Constructors
- Destructors
- operators
- Method definition outside of class definition
- member reference without `this` keyword.
This is implemented using a very simple lexer/parser allowing semantic traversal.
Pull Request: https://projects.blender.org/blender/blender/pulls/144025
This works by wrapping the entry point call inside a
`main` function.
Since resources are still defined in global space,
function accessing these are marked with a custom
attribute. This custom attribute expands in a
`#ifdef` guard for the matching stage.
This is a temporary solution and will eventually
be lifted once we support SRD.
### TODO
- [ ] Implement `[[gpu::vertex/fragment_function]]`.
Pull Request: https://projects.blender.org/blender/blender/pulls/139233
Allows basic usage of templated functions.
There is no support for templated struct.
Benefit:
- More readable than macros in shader sources.
- Compatible with C++ tools.
- More sharing possible with host C++ code.
Requirements/Limitations:
- No default arguments to template parameters.
- Must use explicit instantiation for all variant needed.
- Explicit instantiation needs to **not** use argument deduction.
- Calls to template needs to have all template argument explicit
or all implicit.
- Template overload is not supported (redefining the same template
with different template argument or function argument types).
Currently implemented as Macros inside the build-time pre-pocessor,
but that could change to copy-paste to allow better error reporting.
However, the Macros keep the shader code reduced in the final binary
and allow different file to declare different instantiation.
The implementation is done by declaring overloads for each explicit
instantiation.
If a template has arguments not present in function
arguments, then all arguments **values** are appended to the
function name. The explicit template callsite is then modified to use
`TEMPLATE_GLUE` which will call the correct function. This is
why template argument deduction is not supported in this case.
Rel #137446
Pull Request: https://projects.blender.org/blender/blender/pulls/137441
This adds basic unrolling support for 2 syntax:
- `[[gpu::unroll]]` which does full loop unrolling
- `[[gpu::unroll(x)]]` which unrolls `x` iteration
Nesting is supported.
This change is motivated by the added cost in compilation
and execution time that some loops have even if they have
compile time defined iteration counts.
The syntax is inspired by `GL_EXT_control_flow_attributes`.
However, we might want to have our own prefix to show it is
a blender specific feature and that it differs from the standard.
I propose `[[gpu::unroll]]`.
In the future, we could extend this to support more directives that
can be expanded to backend specific extension / syntax. This would
avoid readability issue an error prone copy paste of large amount
of preprocessor directives.
Currently, given that GL's GLSL flavor doesn't support
any of these attributes, the preprocessor does some copy-pasting
that does the unrolling at the source level. Note that the added
`#line` allow for correct error logging.
For the `[[gpu::unroll]]` syntax, the `for` declaration
needs to follow a specific syntax to deduce the number
of loop iteration.
This variant removes the continue condition between iteration,
so all iterations are evaluated. This could be modified
using a special keyword.
For the `[[gpu::unroll(n)]]` syntax, the usercode needs
to make sure that `n` is large enough to cover all iterations
as the loop is completely removed.
We could add shader `assert` to make sure that there is
never a remaining iteration.
This behavior is usually different from what you see in other
implementation as we do not keep a loop at all. Usually, compilers
still keep the loop if it is not unrolled fully. But given we don't
have IR, this is the best we can do.
`break` and `continue` statement are forbidden at the unrolled loop
scope level. Nested loop and switch can contain these keywords.
This is accounted for by checks in the pre-processor.
Only `for` loops are supported for now. There are no real
incentive to add support for `while` given how rare it is
in the shader codebase.
Rel #137446
Pull Request: https://projects.blender.org/blender/blender/pulls/137444
This avoid having to guards functions that are
only available in fragment shader stage.
Calling the function inside another stage is still
invalid and will yield a compile error on Metal.
The vulkan and opengl glsl patch need to be modified
per stage to allow the fragment specific function
to be defined.
This is not yet widely used, but a good example is
the change in `film_display_depth_amend`.
Rel #137261
Pull Request: https://projects.blender.org/blender/blender/pulls/138280
Previously spell checker ignored text in single quotes however this
meant incorrect spelling was ignored in text where it shouldn't have
been.
In cases single quotes were used for literal strings
(such as variables, code & compiler flags),
replace these with back-ticks.
In cases they were used for UI labels,
replace these with double quotes.
In cases they were used to reference symbols,
replace them with doxygens symbol link syntax (leading hash).
Apply some spelling corrections & tweaks (for check_spelling_* targets).
Do this only when applicable.
This allow better compile time checking in Shader C++ compilation.
Moreover, this allows to have `constexpr` in shared code between
C++ and GLSL.
After investigation the `const` keyword in GLSL has the same
semantic than C/C++.
Rel #137333 and #137446
Pull Request: https://projects.blender.org/blender/blender/pulls/137497
This unify the C++ and GLSL codebase style.
The GLSL types are still in the backend compatibility
layers to support python shaders. However, the C++
shader compilation layer doesn't have them to enforce
correct type usage.
Note that this is going to break pretty much all PRs
in flight that targets shader code.
Rel #137261
Pull Request: https://projects.blender.org/blender/blender/pulls/137369
They are actually already some literals with the `f` suffix
that are in our shader codebase and we never had problem in
the past 5 years (or even 8 years).
So I think it is safe to do and improves convergence of codestyles.
Pull Request: https://projects.blender.org/blender/blender/pulls/137352
Continuation of #131332.
Including built-in headers in VS2019 ends up including `corecrt_math.h`
as a side effect, which has many functions that overlap in name with
our stubs.
This puts the conflicting functions inside its own namespace (`glsl`)
and declares macros for them.
(Note this has the side effect of not allowing us to use those as
variable names)
This also removes the `<cassert>` and `<cstdio>` includes.
Pull Request: https://projects.blender.org/blender/blender/pulls/131386
This avoid stack overflow on GCC because types were getting too
large (70 bytes for a float4) and created a lot of static
memory for UBOs declarations.
