feat(editor): add --gen-mesh-grid subdivided plane

Flat plane on the XY plane subdivided into NxN cells. Useful for
LOD demos, deformable surfaces (later --displace passes), and
testbench geometry that needs many triangles for benchmarking.

Default size 1.0 (centered on origin), subdivisions hard-capped at
256 so a typo can't generate 130k+ vertices accidentally.

Vertex count is (N+1)² and triangles are 2N², both reported in the
output so the user sees the budget. Verified: N=16 size=4 produces
289 verts / 512 tris.
This commit is contained in:
Kelsi 2026-05-07 16:36:50 -07:00
parent c9f054657d
commit b5bd7cdc05

View file

@ -547,6 +547,8 @@ static void printUsage(const char* argv0) {
std::printf(" Compose a procedural mesh + matching PNG texture wired into the WOM's batch\n");
std::printf(" --gen-mesh-stairs <wom-base> <steps> [stepHeight] [stepDepth] [width]\n");
std::printf(" Procedural straight staircase along +X with N steps (default 5 / 0.2 / 0.3 / 1.0)\n");
std::printf(" --gen-mesh-grid <wom-base> <subdivisions> [size]\n");
std::printf(" Subdivided flat plane on XY (NxN cells, 2N² triangles); useful for LOD demos\n");
std::printf(" --gen-mesh-from-heightmap <wom-base> <heightmap.png> [scaleXZ] [scaleY]\n");
std::printf(" Convert a grayscale PNG into a heightmap mesh (W×H verts, 2(W-1)(H-1) tris)\n");
std::printf(" --export-mesh-heightmap <wom-base> <out.png> <W> <H>\n");
@ -1016,7 +1018,7 @@ int main(int argc, char* argv[]) {
"--bench-migrate-data-tree", "--list-data-tree-largest",
"--export-data-tree-md", "--gen-texture", "--gen-mesh", "--gen-mesh-textured",
"--add-texture-to-mesh", "--add-texture-to-zone",
"--gen-mesh-stairs", "--gen-texture-gradient",
"--gen-mesh-stairs", "--gen-mesh-grid", "--gen-texture-gradient",
"--gen-mesh-from-heightmap", "--export-mesh-heightmap",
"--scale-mesh", "--translate-mesh", "--strip-mesh",
"--gen-texture-noise", "--rotate-mesh",
@ -18005,6 +18007,96 @@ int main(int argc, char* argv[]) {
std::printf(" span : %.3fL × %.3fH × %.3fW\n",
steps * stepDepth, steps * stepHeight, width);
return 0;
} else if (std::strcmp(argv[i], "--gen-mesh-grid") == 0 && i + 2 < argc) {
// Flat plane subdivided into NxN cells. Useful for LOD
// demos, deformable surfaces (later --displace passes),
// testbench geometry that needs many triangles. Default
// size is 1.0 (centered on origin). Hard cap at N=256
// so a typo doesn't generate a mesh with 130k+ vertices.
std::string womBase = argv[++i];
int N = 0;
try { N = std::stoi(argv[++i]); }
catch (...) {
std::fprintf(stderr,
"gen-mesh-grid: <subdivisions> must be an integer\n");
return 1;
}
if (N < 1 || N > 256) {
std::fprintf(stderr,
"gen-mesh-grid: subdivisions %d out of range (1..256)\n", N);
return 1;
}
float size = 1.0f;
if (i + 1 < argc && argv[i + 1][0] != '-') {
try { size = std::stof(argv[++i]); } catch (...) {}
}
if (size <= 0.0f) {
std::fprintf(stderr,
"gen-mesh-grid: size must be positive\n");
return 1;
}
if (womBase.size() >= 4 &&
womBase.substr(womBase.size() - 4) == ".wom") {
womBase = womBase.substr(0, womBase.size() - 4);
}
wowee::pipeline::WoweeModel wom;
wom.name = std::filesystem::path(womBase).stem().string();
wom.version = 3;
// (N+1)x(N+1) vertices on the XY plane centered on origin,
// Z=0. Normals all point +Z; UVs are 0..1 across the grid.
float halfSize = size * 0.5f;
float cellSize = size / N;
for (int j = 0; j <= N; ++j) {
for (int k = 0; k <= N; ++k) {
wowee::pipeline::WoweeModel::Vertex v;
v.position = glm::vec3(-halfSize + k * cellSize,
-halfSize + j * cellSize,
0.0f);
v.normal = glm::vec3(0, 0, 1);
v.texCoord = glm::vec2(static_cast<float>(k) / N,
static_cast<float>(j) / N);
wom.vertices.push_back(v);
}
}
int stride = N + 1;
for (int j = 0; j < N; ++j) {
for (int k = 0; k < N; ++k) {
uint32_t a = j * stride + k;
uint32_t b = a + 1;
uint32_t c = a + stride;
uint32_t d = c + 1;
wom.indices.push_back(a);
wom.indices.push_back(c);
wom.indices.push_back(b);
wom.indices.push_back(b);
wom.indices.push_back(c);
wom.indices.push_back(d);
}
}
wom.boundMin = glm::vec3(-halfSize, -halfSize, 0);
wom.boundMax = glm::vec3( halfSize, halfSize, 0);
wom.boundRadius = glm::length(wom.boundMax - wom.boundMin) * 0.5f;
wowee::pipeline::WoweeModel::Batch b;
b.indexStart = 0;
b.indexCount = static_cast<uint32_t>(wom.indices.size());
b.textureIndex = 0;
b.blendMode = 0;
b.flags = 0;
wom.batches.push_back(b);
wom.texturePaths.push_back("");
std::filesystem::path womPath(womBase);
std::filesystem::create_directories(womPath.parent_path());
if (!wowee::pipeline::WoweeModelLoader::save(wom, womBase)) {
std::fprintf(stderr,
"gen-mesh-grid: failed to save %s.wom\n", womBase.c_str());
return 1;
}
std::printf("Wrote %s.wom\n", womBase.c_str());
std::printf(" subdivisions : %d (%dx%d cells)\n", N, N, N);
std::printf(" size : %.3f\n", size);
std::printf(" vertices : %zu = (N+1)²\n", wom.vertices.size());
std::printf(" triangles : %zu = 2N²\n", wom.indices.size() / 3);
return 0;
} else if (std::strcmp(argv[i], "--gen-mesh-from-heightmap") == 0 && i + 2 < argc) {
// Convert a grayscale PNG into a heightmap mesh. Each
// pixel becomes one vertex; brightness becomes Y. The