fix: sync #dpr immediately after controller reinit on alphaEnabled toggle#23
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…ggle When alphaEnabled (or webGPUEnabled) changes, the init effect tears down the old controller and creates a new one. The ResizeObserver only fires when the container *size* changes, so it never re-fires for a toggle — leaving the simulation with the default #dpr=1 until something else triggers a resize. With wrong #dpr the pointer-to-UV coordinate transform is off: px = (cssX * 1) / (cssW * DPR * qualityDpr) -- wrong px = (cssX * DPR * qualityDpr) / (cssW * DPR * qualityDpr) -- correct Fix: call controller.resize(initW, initH) immediately after construction so the correct DPR is pushed into the simulation from frame 0, matching the behaviour the user already sees when changing pixelRatio. Also null-guard FluidController#resize for the async WebGPU path where #sim is temporarily null while the adapter request is in flight. Closes #16 Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
A fresh FluidSimulation starts with #mouse.{x,y,targetX,targetY} = 0.
The first handleMove call computes dx = currentX - 0, producing a large
velocity vector that draws a fluid streak from the top-left corner to the
cursor on every controller reinit (alphaEnabled toggle, etc.).
Fix: skip the dx/dy calculation on the very first handleMove and just seed
the mouse position instead, so subsequent moves only measure real deltas.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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Summary
alphaEnabled(orwebGPUEnabled) is toggledFluidController, but theResizeObserveronly fires when the container dimensions change — not when onlyalphaEnabledchanges. This leftsimulation.#dpr = 1(the default) so the pointer-to-UV coordinate transform was wrong until something else triggered a resizecontroller.resize(initW, initH)right after construction inuseFluid.tsto push the correct DPR into the simulation from frame 0FluidController#resize(!→?) for the async WebGPU path where#simis temporarilynullwhile the adapter request is in flightTest plan
npm test -- --run)npm run build)alphaEnabledoff — cursor and splat should be co-locatedalphaEnabledback on — still correctpixelRatio/simResolutionquality changesCloses #16
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