fix: Using floating point math for arcs.#173
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ooxi merged 1 commit intogerbv:mainfrom May 25, 2023
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Arcs and lines don't always line up when the image is zoomed out because gdk expects integers so we do a lot of integer math. For example, under a lot of zoom out, we might be looking at arcs circles with a diameter of 5. When dividing by 2 to compute the radius, this causes a problem. The solution is to do as much floating-point math as possible and only convert to integer at the very end, when we call the GDK functions to draw. In testing, this fixed gerbv#167.
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To test, download the files from #167 and then compile and run gerbv like this: Go to rendering mode "Fast, with XOR". Then, click on the "-" in the menu bar 6 times. Before: After: If I zoom out even further than I get some more artifacts but this is at least better than what we had before. The best solution would be to do all math in floating-point and only convert to integer when necessary. |
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Thank you! I'll finish the release of 2.9.7 and then merge this |
rampageservices
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Mar 10, 2026
Replace integer-truncating division (/ 2, >> 1) with round(... / 2.0) when computing top-left coordinates for circles, macro primitives (prim1, prim6, prim7), rectangles, and ovals in the GDK renderer. Integer truncation causes off-by-one positioning of concentric apertures (e.g. pad + hole) at low zoom levels, making them appear misaligned. This extends the fix from PR gerbv#173 (which addressed arcs only) to all remaining shape primitives. Fixes gerbv#167
This was referenced Mar 10, 2026
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Arcs and lines don't always line up when the image is zoomed out because gdk expects integers so we do a lot of integer math. For example, under a lot of zoom out, we might be looking at arcs circles with a diameter of 5. When dividing by 2 to compute the radius, this causes a problem.
The solution is to do as much floating-point math as possible and only convert to integer at the very end, when we call the GDK functions to draw. In testing, this fixed #167.