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feat(editor): extend --gen-mesh with cone shape

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Adds a cone with apex at +Y, base at Y=0. radius=size/2,
height=size, 24 side segments → 76 verts / 72 tris.

Side normals are computed from the slope (cos/sin of segment angle
× H/sqrt(H²+r²) for XZ, r/sqrt(H²+r²) for Y) so shading shows the
slant correctly. Apex vertex is duplicated per segment so each
triangle carries the segment-specific normal — the cone shades as
a smooth curved surface rather than a faceted prism.

Bottom cap is a separate fan with flat -Y normal. Base at Y=0
(rather than centered) makes it natural to drop on a surface
without manual offset — matches typical "standing on the floor"
placement.

Useful for spikes, party hats, traffic cones, magic-circle pillars.
Help text on both --gen-mesh and --gen-mesh-textured updated to
advertise the new shape.

Verified: cone 2.0 → 76 verts / 72 tris / bounds (-1,0,-1) to
(1,2,1). The 6-shape primitive set is now cube/plane/sphere/cylinder/
torus/cone.
This commit is contained in:
Kelsi 2026-05-07 05:08:39 -07:00
parent 3dc18d96ab
commit fb775ac208
1 changed files with 71 additions and 3 deletions
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74
tools/editor/main.cpp
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@ -528,9 +528,9 @@ static void printUsage(const char* argv0) {
std::printf(" Synthesize a placeholder texture (solid hex color or 'checker'/'grid'); default 256x256\n");
std::printf(" --add-texture-to-zone <zoneDir> <png-path> [renameTo]\n");
std::printf(" Copy an existing PNG into <zoneDir> (optionally renaming it on the way in)\n");
std::printf(" --gen-mesh <wom-base> <cube|plane|sphere|cylinder|torus> [size]\n");
std::printf(" --gen-mesh <wom-base> <cube|plane|sphere|cylinder|torus|cone> [size]\n");
std::printf(" Synthesize a procedural WOM primitive with proper normals, UVs, and bounds\n");
std::printf(" --gen-mesh-textured <wom-base> <cube|plane|sphere|cylinder|torus> <colorHex|pattern> [size]\n");
std::printf(" --gen-mesh-textured <wom-base> <cube|plane|sphere|cylinder|torus|cone> <colorHex|pattern> [size]\n");
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");
@ -15355,9 +15355,77 @@ int main(int argc, char* argv[]) {
wom.indices.push_back(d);
}
}
} else if (s == "cone") {
// Cone with apex at +Y. radius=size/2, height=size.
// 24 side segments. Side has smooth radial-ish normals
// (slanted up by half the slope angle) for a curved
// shaded surface; bottom cap has flat -Y normal.
const int segments = 24;
float r = h;
float H = size;
// Slant length used for the side normal Y component.
// Side normal direction: (cos(a), nyComponent, sin(a))
// where the slope is r/H per unit of horizontal travel.
// Normalize so the normal has unit length.
float sideXZScale = H / std::sqrt(H * H + r * r);
float sideY = r / std::sqrt(H * H + r * r);
// Side ring (apex repeated per segment so each tri has
// its own apex vertex with the correct normal).
for (int sg = 0; sg <= segments; ++sg) {
float u = static_cast<float>(sg) / segments;
float ang = u * 2.0f * 3.14159265358979f;
float ca = std::cos(ang), sa = std::sin(ang);
// Base vertex (Y = 0).
addVertex(r * ca, 0.0f, r * sa,
sideXZScale * ca, sideY, sideXZScale * sa,
u, 1.0f);
// Apex vertex (Y = H), one per ring step so the
// top vertex carries the segment-specific normal.
addVertex(0.0f, H, 0.0f,
sideXZScale * ca, sideY, sideXZScale * sa,
u, 0.0f);
}
// Side triangle indices.
for (int sg = 0; sg < segments; ++sg) {
uint32_t base = sg * 2;
// Two tris per quad band. The apex collapses to a
// point, so really one triangle per segment, but
// emitting both keeps the indexing uniform across
// the cylinder/cone code paths.
uint32_t a = base + 0; // base k
uint32_t b = base + 1; // apex k
uint32_t c = base + 2; // base k+1
uint32_t d = base + 3; // apex k+1
wom.indices.push_back(a);
wom.indices.push_back(c);
wom.indices.push_back(b);
// Second triangle would be (b,c,d) but b == d at
// the apex visually — we still emit it so the
// per-vertex normals on b and d shade the joining
// seam smoothly.
wom.indices.push_back(b);
wom.indices.push_back(c);
wom.indices.push_back(d);
}
// Bottom cap fan (flat -Y normal).
uint32_t botCenter = static_cast<uint32_t>(wom.vertices.size());
addVertex(0.0f, 0.0f, 0.0f, 0.0f, -1.0f, 0.0f, 0.5f, 0.5f);
uint32_t botRingStart = static_cast<uint32_t>(wom.vertices.size());
for (int sg = 0; sg <= segments; ++sg) {
float u = static_cast<float>(sg) / segments;
float ang = u * 2.0f * 3.14159265358979f;
float ca = std::cos(ang), sa = std::sin(ang);
addVertex(r * ca, 0.0f, r * sa, 0.0f, -1.0f, 0.0f,
0.5f + 0.5f * ca, 0.5f - 0.5f * sa);
}
for (int sg = 0; sg < segments; ++sg) {
wom.indices.push_back(botCenter);
wom.indices.push_back(botRingStart + sg + 1);
wom.indices.push_back(botRingStart + sg);
}
} else {
std::fprintf(stderr,
"gen-mesh: shape must be cube, plane, sphere, cylinder, or torus (got '%s')\n",
"gen-mesh: shape must be cube, plane, sphere, cylinder, torus, or cone (got '%s')\n",
shape.c_str());
return 1;
}