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Docs: Improve docstring for DDA algorithm #13906

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Docs: Improve docstring for DDA algorithm
jeanne-boussonniere Nov 13, 2025
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7 changes: 7 additions & 0 deletions graphics/digital_differential_analyzer_line.py
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Expand Up @@ -7,6 +7,13 @@ def digital_differential_analyzer_line(
"""
Draws a line between two points using the DDA algorithm.

This algorithm works by calculating the dx (change in x) and dy;(change in y) and then iteratively
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@ayushHardeniya ayushHardeniya Nov 14, 2025

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After dy - ";" is put by mistake, maybe, so remove it or adjust accordingly.

steps along the dominant axis,incrementing the other axis by a fractional amount (the slope).
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@ayushHardeniya ayushHardeniya Nov 14, 2025

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The algorithm actually steps along both axes simultaneously. The calculation of the increments ($X_{inc}$ and $Y_{inc}$) ensures that the coordinate along the dominant axis (the one with the larger $\Delta$) is guaranteed to change by exactly 1 unit (or $-1$) in each step, while the coordinate along the non-dominant axis changes by a fractional amount (the slope). The algorithm doesn't "step along" just the dominant axis; it increments both $x$ and $y$ in every single step.

It is notable for its simplicity but also for its main disadvantage:
it relies on floating-point arithmetic at every step, which is computationally slow.
It is generally outperformed by Bresenham's algorithm, which achieves
the same result using only integer-based math.

Args:
- p1: Coordinates of the starting point.
- p2: Coordinates of the ending point.
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