Freestyle's pipeline is now fully controllable at the layer level. It can be used:
- in any render layer
- with as many style modules per layer
DETAILS:
Freestyle usage has not changed:
- all the configuration happens in the "Freestyle" render panel, after it is enabled in the "Output" panel with the 'Freestyle' toggle.
- each render layer can choose to render Freestyle strokes by togglingo on 'FrSt' (in the "Render Layers" panel)
- it is fully compatible with compositor nodes
In the "Freestyle" panel, a render layer is selected via the menu list next to the "Render Layer:" label. The options displayed below are those of the currently selected render layer (and are not global to all render layers, as was previously the case).
Style modules are added by pressing the lower button "Add style module". Once added, the following operations are possible:
- deletion (cross)
- reordering (up/down arrows)
- toggling of display (check)
The order of the style modules follows Freestyle's original convention: the modules in the list from top to bottom are respectively the first to the last composited in the render layer. For example, if the module list is "contour" followed by "cartoon", the "cartoon" strokes are rendered on top of the "contour" strokes.
The "Freestyle" panel is constantly synchronized with the "Render Layers" panel: if render layers are added, deleted or toggled off display, Freestyle will take note of the changes.
The current pipeline works as follows:
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for every scene that is being rendered
if Freestyle is enabled globally
Freestyle is initialized
camera and view settings are transferred from Blender to Freestyle
for every render layer
if: - layer is enabled
- layer enabled Freestyle
- the number of displayed style modules is non-zero
canvas is cleared
geometry is transferred from Blender to Freestyle
settings are fixed for current iteration
view map is calculated
strokes are computed in the canvas (based on view map and style modules)
strokes are rendered in separate Blender scene
scene is composited in current layer
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A number of changes were made on the codebase:
- the rendering interface between Freestyle and Blender was simplified. The following naming convention was used: functions that are called from within Blender pipeline are prefixed with 'FRS_', while the variables are prefixed with 'freestyle_'
- Freestyle data structures that were put in Blender's render pipeline were removed
- Freestyle cleans up its data structures on Blender exit and shouldn't leak memory
- to ease the configuration in the "Freestyle" panel, a centralized configuration data structure was used and can be easily extended
LIMITATIONS
Even though the current commit is stable and achieves the intended result, it is not as efficient as it could be:
- the canvas and the style modules are at cleared at each layer-level render
- geometry is reloaded at each frame and is duplicated across render layers
This revision clarifies my understanding of the future role of the view map in the compositor. Unfortunately, contrary to what the original proposal said, it is impossible to provide the view map as a render pass because render passes are defined (RE_pipeline.h) as raw floating-point rects. We will have to determine whether or not to extend the notion of render pass to fully integrate the view map in the compositor.
The render generated from Freestyle's data is currently stored in the original scene's render structure ( as 'freestyle_render'): when the render database is generated, the scene's geometrical data is first imported into Freestyle and strokes are calculated. The generated strokes are used to create a Blender scene, rendered independently. The render result is used in the rendering loop.
The final rendering is performed the same way edge rendering is, in a function ('freestyle_enhance_add') operating on each individual render part. Freestyle strokes are only included if the toggle button "Freestyle" (in the 'Output' panel) is active and if the "Freestyle" render layer is also selected. Freestyle's panel appears when the toggle button 'Freestyle' is active.
IMPORTANT: as of now, rendering ONLY works when OSA is disabled and when Xparts = Yparts = 1. If these settings are not set, a bogus image will be created.
To make the render happen, many modifications had to be made:
- the Canvas::Draw and Operators::create methods no longer render strokes. They only generate shading and locational information.
- a BlenderStrokeRenderer class was added to turn Freestyle's strokes into a Blender scene. Basically, the scene consists of strokes in their projected image 2D coordinates and an orthographic camera centered in the middle of the corresponding canvas. The scene is rendered using vertex colors, in shadeless mode (therefore, no lamp is needed). BlenderStrokeRenderer uses the old GLTextureManager to load textures (as required by the StrokeRenderer class), even though stroke textures are probably not supported (not tested). After the scene is rendered, it is safely and automatically discarded.
- AppCanvas' code was greatly reduced to the bare minimum. The former AppCanvas would use an OpenGL-based back buffer and z buffer to determine the scene's color and depth information. In the future, this data will be determined from the corresponding render passes. Currently, the integration is not achieved so all style modules using depth/color information are sure to fail.
- before, Freestyle needed an OpenGL context to determine the camera's information and to compute the view map. As of now, the modelview and projection matrices are fully determined using data provided by Blender. This means both perspective and orthographic projections are supported. The AppGLWidget will very soon be removed completely.
IMPORTANT: The setters functions' names were normalized due to constant confusion regarding capitalization. All the function names start with set... instead of Set.... This convention was changed all throughout Freestyle. To use Freestyle as an external renderer, the SWIG library MUST be regenerated.
1. instantiates the config path, the controller and the view
2. sets the controller’s view
3. loads a 3ds file (right now a fixed file)
4. inserts a style module (right now, also fixed)
5. computes the view map
The next and final step is running the Python script. A lot of information are fixed and should be changed to test the following code: see source/blender/freestyle/app_blender/*.cpp and search for fixed paths (starting in /Users/).
I am currently evaluating whether it's worth making Python run on its own environment (right now, the program crashes because of PyImport_AddModule) or whether it should use Blender's Python capabilities. Also, I need to figure out how to integrate the SWIG wrapper dynamic library into the current scheme.
