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.title Drawing to Views
Views are an essential mechanism of the 3d rendering backend and must be thoroughly understood to perform any form of complex rendering.
Overview
Views are refered to by index as an integer value between 0 and 255. There can be no more than 256 views defined.
Each call to a drawing function such as [DrawLines] or [DrawModel] is queued as multiple draw commands on the specified view. When [Frame] is called all views are processed in order, from the lowest to the highest id.
Keep in mind that rendering is deferred and no actual drawing occurs immediately after calling a draw function.
Drawing happens when [Frame] is called and all views are reset after that.
View Properties
The following properties are specified per view:
- View and projection matrices set by [SetViewTransform].
- Clipping rectangle set by [SetViewRect].
- Color/depth/stencil clear set by [SetViewClear].
- Draw command ordering set by [SetViewMode].
- Output buffer set by [SetViewFrameBuffer].
A view accepts a single value for each of these properties. Multiple calls to change the same property of a view will override its current value.
If you need to use different values for a view property you must use additional views even if all other properties remain unchanged.
Views with no queued draw commands are skipped. If you need to force the processing of a view, use [Touch].
Draw Command Queue
Draw commands queued on a view are processed according to the view mode, they are executed:
- In submission order if the view mode is [VM_Sequential].
- In ascending depth order if the view mode is [VM_DepthAscending].
- In descending depth order if the view mode is [VM_DepthDescending].
When the view mode is [VM_DepthAscending] or [VM_DepthDescending], the depth value used to sort draw commands is derived from the draw call depth parameter.
When no depth is specified, 0 is implied.