phaneron/Kelsidavis-WoWee
1
0
Fork 0
mirror of https://github.com/Kelsidavis/WoWee.git synced 2026-05-08 10:03:51 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 2

feat(editor): add --displace-mesh for heightmap displacement on existing meshes

Browse source 
Offsets each vertex along its current normal by heightmap brightness
× scale. UVs determine where each vertex samples the heightmap;
sampling uses bilinear filtering with UV-wrap so repeating UVs
tile correctly.

Pairs naturally with --gen-mesh-grid: gen a flat grid, then
--displace-mesh with a noise PNG to create procedural terrain. Or
use it on a sphere to make a bumpy planet, on a cylinder for tree-
bark deformation, etc.

Output reports the actual delta range produced so the user can
gauge the scale. A hint suggests running --smooth-mesh-normals
afterward since the post-displacement shading would otherwise
follow the original (now-stale) flat normals.

Verified pipeline: --gen-mesh-grid (32×32, 1089 verts) → --gen-
texture-noise → --displace-mesh (scale 2) → bounds X/Y stay ±5
while Z spans 0..1.93.
This commit is contained in:
Kelsi 2026-05-07 16:53:36 -07:00
parent b5bd7cdc05
commit d64d188b13
1 changed files with 100 additions and 0 deletions
Download patch file Download diff file Expand all files Collapse all files

100
tools/editor/main.cpp
View file

@ -549,6 +549,8 @@ static void printUsage(const char* argv0) {
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(" --displace-mesh <wom-base> <heightmap.png> [scale]\n");
std::printf(" Offset each vertex along its normal by heightmap brightness × scale (default 1.0)\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");
@ -1020,6 +1022,7 @@ int main(int argc, char* argv[]) {
"--add-texture-to-mesh", "--add-texture-to-zone",
"--gen-mesh-stairs", "--gen-mesh-grid", "--gen-texture-gradient",
"--gen-mesh-from-heightmap", "--export-mesh-heightmap",
"--displace-mesh",
"--scale-mesh", "--translate-mesh", "--strip-mesh",
"--gen-texture-noise", "--rotate-mesh",
"--center-mesh", "--flip-mesh-normals", "--mirror-mesh",
@ -18097,6 +18100,103 @@ int main(int argc, char* argv[]) {
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], "--displace-mesh") == 0 && i + 2 < argc) {
// Displaces each vertex along its current normal by the
// heightmap brightness × scale. UVs determine where each
// vertex samples the heightmap.
//
// Pairs naturally with --gen-mesh-grid: gen a flat grid,
// then --displace-mesh with a noise PNG to create
// procedural terrain. Or use it on a sphere to make a
// bumpy planet.
std::string womBase = argv[++i];
std::string pngPath = argv[++i];
float scale = 1.0f;
if (i + 1 < argc && argv[i + 1][0] != '-') {
try { scale = std::stof(argv[++i]); } catch (...) {}
}
if (!std::isfinite(scale)) scale = 1.0f;
if (womBase.size() >= 4 &&
womBase.substr(womBase.size() - 4) == ".wom") {
womBase = womBase.substr(0, womBase.size() - 4);
}
namespace fs = std::filesystem;
if (!wowee::pipeline::WoweeModelLoader::exists(womBase)) {
std::fprintf(stderr,
"displace-mesh: %s.wom does not exist\n", womBase.c_str());
return 1;
}
int W, H, comp;
uint8_t* data = stbi_load(pngPath.c_str(), &W, &H, &comp, 1);
if (!data) {
std::fprintf(stderr,
"displace-mesh: cannot read %s (%s)\n",
pngPath.c_str(), stbi_failure_reason());
return 1;
}
auto wom = wowee::pipeline::WoweeModelLoader::load(womBase);
if (!wom.isValid()) {
std::fprintf(stderr,
"displace-mesh: failed to load %s.wom\n", womBase.c_str());
stbi_image_free(data);
return 1;
}
float minDelta = 1e30f, maxDelta = -1e30f;
for (auto& v : wom.vertices) {
// Sample the heightmap with bilinear filtering at
// (u, v). Wrap repeating UVs.
float u = v.texCoord.x - std::floor(v.texCoord.x);
float vv = v.texCoord.y - std::floor(v.texCoord.y);
float fx = u * (W - 1);
float fy = vv * (H - 1);
int x0 = static_cast<int>(fx);
int y0 = static_cast<int>(fy);
int x1 = std::min(x0 + 1, W - 1);
int y1 = std::min(y0 + 1, H - 1);
float tx = fx - x0;
float ty = fy - y0;
auto sample = [&](int x, int y) {
return data[y * W + x] / 255.0f;
};
float a = sample(x0, y0);
float b = sample(x1, y0);
float c = sample(x0, y1);
float d = sample(x1, y1);
float ab = a + (b - a) * tx;
float cd = c + (d - c) * tx;
float h = ab + (cd - ab) * ty;
float delta = h * scale;
v.position += v.normal * delta;
if (delta < minDelta) minDelta = delta;
if (delta > maxDelta) maxDelta = delta;
}
stbi_image_free(data);
// Recompute bounds; normals stay (they're now stale to
// the displaced surface but the user can run --smooth-
// mesh-normals if they want shading to follow the bumps).
wom.boundMin = glm::vec3(1e30f);
wom.boundMax = glm::vec3(-1e30f);
for (const auto& v : wom.vertices) {
wom.boundMin = glm::min(wom.boundMin, v.position);
wom.boundMax = glm::max(wom.boundMax, v.position);
}
wom.boundRadius = glm::length(wom.boundMax - wom.boundMin) * 0.5f;
if (!wowee::pipeline::WoweeModelLoader::save(wom, womBase)) {
std::fprintf(stderr,
"displace-mesh: failed to save %s.wom\n", womBase.c_str());
return 1;
}
std::printf("Displaced %s.wom with %s\n",
womBase.c_str(), pngPath.c_str());
std::printf(" source PNG : %dx%d\n", W, H);
std::printf(" scale : %g\n", scale);
std::printf(" vertices : %zu touched\n", wom.vertices.size());
std::printf(" delta : %.3f to %.3f\n", minDelta, maxDelta);
std::printf(" new bounds : (%.3f, %.3f, %.3f) - (%.3f, %.3f, %.3f)\n",
wom.boundMin.x, wom.boundMin.y, wom.boundMin.z,
wom.boundMax.x, wom.boundMax.y, wom.boundMax.z);
std::printf(" hint : run --smooth-mesh-normals so shading follows the bumps\n");
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