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Fixed gausian rendering #1136

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Merged
untoldengine merged 2 commits into from
Aug 10, 2026
+16 −4
Merged

Fixed gausian rendering #1136

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1230240
[Patch] fixed gaussian not rendering
untoldengine Aug 7, 2026
18f64be
[Bugfix] Use the correct effective camera for gaussian
untoldengine Aug 7, 2026
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19 changes: 15 additions & 4 deletions Sources/UntoldEngine/Systems/GaussianSystem.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -121,14 +121,22 @@ public func executeGaussianFrustumCulling(_ commandBuffer: MTLCommandBuffer) {
profileTotals.dispatchCount += 1

let modelMatrix = simd_mul(worldTransformComponent.space, .identity)
let viewMatrix = cameraComponent.viewSpace
// Entity transforms are never modified when the scene root moves (SceneRootTransform
// applies its offset to the camera instead, as a "virtual camera" trick — see
// SceneRootTransform.swift). worldTransformComponent.space above is therefore in
// entity space, so the camera side of this product must go through
// effectiveViewMatrix, not the raw per-eye viewSpace — otherwise this cull silently
// drifts out of sync with where the draw pass (which already uses
// effectiveViewMatrix) actually renders the splats as soon as the scene root is
// translated/rotated (e.g. via SpatialManipulationSystem's pinch-drag).
let viewMatrix = SceneRootTransform.shared.effectiveViewMatrix(cameraComponent.viewSpace)
let modelViewMatrix = simd_mul(viewMatrix, modelMatrix)

var gaussianUniform = Uniforms()
gaussianUniform.modelViewMatrix = modelViewMatrix
gaussianUniform.viewMatrix = viewMatrix
gaussianUniform.modelMatrix = modelMatrix
gaussianUniform.cameraPosition = cameraComponent.localPosition
gaussianUniform.cameraPosition = SceneRootTransform.shared.effectiveCameraPosition(cameraComponent.localPosition)
gaussianUniform.projectionMatrix = renderInfo.perspectiveSpace

var totalSplats = UInt32(gaussianComponent.splatCount)
Expand Down Expand Up @@ -251,7 +259,10 @@ public func executeGaussianDepth(_ commandBuffer: MTLCommandBuffer) {

let modelMatrix = simd_mul(worldTransformComponent.space, .identity)

let viewMatrix: simd_float4x4 = cameraComponent.viewSpace
// See the matching comment in executeGaussianFrustumCulling: worldTransformComponent
// is in entity space, so this must be the scene-root-corrected view, not the raw
// per-eye viewSpace.
let viewMatrix: simd_float4x4 = SceneRootTransform.shared.effectiveViewMatrix(cameraComponent.viewSpace)

let modelViewMatrix = simd_mul(viewMatrix, modelMatrix)

Expand All @@ -269,7 +280,7 @@ public func executeGaussianDepth(_ commandBuffer: MTLCommandBuffer) {

gaussianUniform.modelMatrix = modelMatrix

gaussianUniform.cameraPosition = cameraComponent.localPosition
gaussianUniform.cameraPosition = SceneRootTransform.shared.effectiveCameraPosition(cameraComponent.localPosition)

gaussianUniform.projectionMatrix = renderInfo.perspectiveSpace

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1 change: 1 addition & 0 deletions Sources/UntoldEngineXR/UntoldEngineXR.swift
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Expand Up @@ -796,6 +796,7 @@
snapshot.timing.cullingMs += cullingMs
}
#endif
executeGaussianFrustumCulling(commandBuffer)
executeGaussianDepth(commandBuffer)
executeRadixSort(commandBuffer)
EngineProfiler.shared.endScope(.renderPrep)
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