cajeta.xpu.mesh.MeshSimplifier — the appearance-preserving Garland–Heckbert edge-collapse mesh simplifier, built on Qem. A mesh is an indexed triangle soup in the canonical vertex-buffer layout: a flat float32[] of vertex positions (x, y, z interleaved) and an int32[] of triangle corner indices (three per triangle). The simplifier proceeds in two phases: accumulate a per-vertex error quadric (accumulateQuadrics), then repeatedly collapse the cheapest edge (simplify), moving each merged vertex to its error-minimizing position — so flat regions collapse at zero cost while curved and creased regions resist. Quadrics live in a flat float32[] (16 row-major entries per vertex) because a Matrix[] cannot be allocated; vertexQuadric reconstructs one on demand.

package snip.mesh;

import cajeta.xpu.mesh.MeshSimplifier;

public final class Demo {
    public static void run() {
        // Two triangles sharing an edge: 4 vertices (x, y, z each), 6 indices.
        float32[] positions = heap float32[12];
        positions[3] = 1.0f;                      // v1 = (1, 0, 0)
        positions[7] = 1.0f;                      // v2 = (0, 1, 0)
        positions[9] = 1.0f;  positions[10] = 1.0f;   // v3 = (1, 1, 0)
        int32[] indices = heap int32[6];
        indices[1] = 1;  indices[2] = 2;          // (0, 1, 2)
        indices[3] = 1;  indices[4] = 3;  indices[5] = 2;   // (1, 3, 2)
        float32[] quadrics #= MeshSimplifier.accumulateQuadrics(positions, indices, 4);
        int32[] survivors #= MeshSimplifier.simplify(positions, indices, 4, 1);
        return;
    }
}

Methods

Signature
`static #float32[] accumulateQuadrics(float32[] positions, int32[] indices, int32 vertexCount)` ⚑	Accumulate a Garland–Heckbert error quadric per vertex into a flat `float32[]` (16 row-major entries per vertex; entry `v16 + r4 + c`)
`static Matrix<float32,4,4> vertexQuadric(float32[] quadrics, int32 v)`	Reconstruct vertex `v`’s accumulated quadric as a `Matrix<float32,4,4>` from the flat store
`static #int32[] simplify(float32[] positions, int32[] indices, int32 vertexCount, int32 targetTriangleCount)` ⚑	Iterative edge collapse down to at most `targetTriangleCount` triangles, returning the surviving index list (length a multiple of 3); `positions` is mutated in place

⚑ = @EntryPoint

MeshSimplifier

Methods

See also