高斯泼溅查看器

Load a binary array of splats where each entry stores position, scale, rotation quaternion, RGBA colour. In a worker, compute each splat's 3D covariance from scale and rotation, and on every camera change sort splat indices by view depth with a 16-bit counting sort, then post the order back. Render one instanced quad per splat; in the vertex shader project the covariance with the Jacobian of the perspective projection to get a 2D ellipse and size the quad to about three sigma. In the fragment shader compute alpha as opacity times exp(-0.5 d^T Σ^-1 d) and blend back to front with premultiplied alpha.