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Diffstat (limited to 'third_party/rust/wpf-gpu-raster/README.md')
| -rw-r--r-- | third_party/rust/wpf-gpu-raster/README.md | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/third_party/rust/wpf-gpu-raster/README.md b/third_party/rust/wpf-gpu-raster/README.md new file mode 100644 index 0000000000..1d4756b13f --- /dev/null +++ b/third_party/rust/wpf-gpu-raster/README.md @@ -0,0 +1,22 @@ +This is a port of the WPF hardware rasterizer code to Rust. That +rasterizer is predecessor to the Direct2D rasterizer. Direct2D still +uses a similar technique when run on hardware that does not support +Target Independent Rasterization. + +Design +====== + +The general algorithm used for rasterization is a vertical sweep of +the shape that maintains an active edge list. The sweep is done +at a sub-scanline resolution and results in either: + 1. Sub-scanlines being combined in the coverage buffer and output + as "complex scans". These are emitted as lines constructed out + of triangle strips. + 2. Simple trapezoids being recognized in the active edge list + and output using a faster simple trapezoid path. + +Bezier flattening is done using an approach that uses forward differencing +of the error metric to compute a flattened version that would match a traditional +adaptive recursive flattening. + + |