This is a playground repository that I use to compare various implementations of 'cell' based rasterizers. All rasterizers implemented here use the same algorithm for rasterization, but use different ways of storing rasterized cells. The rasterizer itself contains an optimized renderLine() implementation that differs compared to FreeType/AGG rasterizer in the following:
- It's optimized to use less division than an original AGG/FreeType implementation.
- It's optimized to not use call to renderHLine() compared to AGG/FreeType.
- It doesn't produce different cells for ascending and descending lines, if you rasterize the same shape twice, but each having a different direction, nothing will be drawn (all cells will be zero).
The following rasterizers are provided:
RasterizerA1- The simplest possible rasterizer. Uses W*H cell matrix and iterates all cells during
render(). The idea behind this rasterizer is to provide the most basic implementation that should be used as a reference. - Allocation requirements:
W * H * sizeof(Cell)
- The simplest possible rasterizer. Uses W*H cell matrix and iterates all cells during
RasterizerA2- Similar to
RasterizerA1, but uses a global[yMin..yMax]boundary per rasterizer and[xMin..xMax]boundary per scanline. This allows to only focus on cells where actually some rendering happened and to quickly skip cells that are outside of the rendered shape. - Allocation requirements:
W * H * sizeof(Cell) + H * sizeof(Bounds)
- Similar to
RasterizerA3- Similar to
RasterizerA1, but uses a global[yMin..yMax]boundary per rasterizer and uses bit-array per each scanline where each bit represents N pixels. Rasterizer marks all bits (that represent pixels) where something happened and renderer then bit-scans each scanline to find areas that need to be composited. This approach is much faster thanA1andA2when rendering to large buffers as bit-scannling is faster than iterating over[xMin..xMax]pixels. - Allocation requirements:
W * H * sizeof(Cell) + H * NumBitWordsPerScanline
- Similar to
render_bench is a simple application that compares the performance of various rasterizers rendering into buffers of various sizes.
render_cmd is a simple application that can be used to render something to a pixel-buffer and then store the result as BMP image.
Simple usage of the render_cmd:
$ ./re
53F6
nder_cmd --output=render_cmd.bmp --width=256 --height=256 10 10 240 80 120 240The resulting render_cmd.bmp image: