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WIP stl parser

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This commit is contained in:
Alex Selimov 2026-09-11 23:14:51 -04:00
parent 7321207074
commit 7fd66963ca
3 changed files with 155 additions and 9 deletions
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2
zigsdof/src/io.zig
View file

@ -25,7 +25,7 @@ pub fn jsonFileToSimConfig(
io: std.Io,
) !drone.QuadCopterSim {
const cwd = std.Io.Dir.cwd();
cons file = try cwd.openFile(io, file_path, .{ .mode = .read_only });
const file = try cwd.openFile(io, file_path, .{ .mode = .read_only });
defer file.close(io);
var file_reader = file.reader(io, &.{});

9
zigsdof/src/main.zig
View file

@ -6,12 +6,5 @@ test "main" {
_ = @import("./forces.zig");
_ = @import("./integration.zig");
_ = @import("./io.zig");
}
test "how ptrs work" {
var ptr: *usize = 0;
var val = 1;
ptr = val;
val = 2;
std.testing.expect(*ptr == 1);
_ = @import("./stl.zig");
}

153
zigsdof/src/stl.zig Normal file
View file

@ -0,0 +1,153 @@
const std = @import("std");
const vec3 = @import("./vec3.zig");
fn vecToFixedPoint(vec: vec3.Vec3F64, digits: u5) [3]u64 {
return .{
@round(vec.x() * std.math.pow(f64, 10.0, digits)),
@round(vec.y() * std.math.pow(f64, 10.0, digits)),
@round(vec.z() * std.math.pow(f64, 10.0, digits)),
};
}
pub const Mesh = struct {
vertices: std.ArrayList(vec3.Vec3F64),
triangle_vertices: std.ArrayList([3]usize),
triangle_normals: std.ArrayList(vec3.Vec3F64),
pub fn fromFile(
file_path: []const u8,
allocator: std.mem.Allocator,
io: std.Io,
) !Mesh {
const cwd = std.Io.Dir.cwd();
const file = try cwd.openFile(io, file_path, .{ .mode = .read_only });
defer file.close(io);
var file_reader = file.reader(io, &.{});
const bytes = try file_reader.interface.allocRemaining(allocator, .unlimited);
defer allocator.free(bytes);
return fromByteArray(bytes, allocator);
}
pub fn fromByteArray(
bytes: []const u8,
allocator: std.mem.Allocator,
) !Mesh {
// Skip header
var offset: usize = 80;
const triangle_num: u32 = std.mem.readInt(u32, @ptrCast(bytes[offset .. offset + 4].ptr), .little);
offset += 4;
var triangle_vertices: std.ArrayList([3]usize) = try .initCapacity(allocator, triangle_num);
var triangle_normals: std.ArrayList(vec3.Vec3F64) = try .initCapacity(allocator, triangle_num);
var vertices: std.ArrayList(vec3.Vec3F64) = try .initCapacity(allocator, triangle_num * 3);
var vertex_map: std.AutoHashMap([3]u64, usize) = .init(allocator);
defer vertex_map.deinit();
for (0..triangle_num) |_| {
var normal = vec3.Vec3F64.init(0, 0, 0);
inline for (0..3) |i| {
const bits = std.mem.readInt(
u32,
@ptrCast(bytes[offset .. offset + 4].ptr),
.little,
);
offset += 4;
const val: f32 = @bitCast(bits);
normal.data[i] = val;
}
var indices: [3]usize = .{ 0, 0, 0 };
inline for (0..3) |i| {
var vertex = vec3.Vec3F64.init(0, 0, 0);
inline for (0..3) |j| {
const bits = std.mem.readInt(
u32,
@ptrCast(bytes[offset .. offset + 4].ptr),
.little,
);
offset += 4;
const val: f32 = @bitCast(bits);
vertex.data[j] = val;
}
const gop = try vertex_map.getOrPut(vecToFixedPoint(vertex, 5));
if (gop.found_existing) {
indices[i] = gop.value_ptr.*;
} else {
const new_idx = vertices.items.len;
try vertices.append(allocator, vertex);
gop.value_ptr.* = new_idx;
indices[i] = new_idx;
}
}
try triangle_vertices.append(allocator, indices);
try triangle_normals.append(allocator, normal);
}
std.debug.print("{}", .{vertices});
return .{
.triangle_vertices = triangle_vertices,
.triangle_normals = triangle_normals,
.vertices = vertices,
};
}
pub fn deinit(mesh: *Mesh, allocator: std.mem.Allocator) void {
mesh.triangle_vertices.deinit(allocator);
mesh.triangle_normals.deinit(allocator);
mesh.vertices.deinit(allocator);
}
};
test "Verify fixed point conversion works" {
const vec = vec3.Vec3F64.init(1.0, 2.134, 1010.11);
const fixed_point = vecToFixedPoint(vec, 2);
try std.testing.expect(fixed_point[0] == 100);
try std.testing.expect(fixed_point[1] == 213);
try std.testing.expect(fixed_point[2] == 101011);
}
test "Test binary stl is parsed correctly" {
const binary_stl = "\x42\x69\x6e\x61\x72\x79\x20\x53\x54\x4c\x3a\x20\x32\x20\x74\x72\x69\x61" ++
"\x6e\x67\x6c\x65\x73\x3b\x20\x6e\x6f\x72\x6d\x61\x6c\x73\x20\x66\x72\x6f" ++
"\x6d\x20\x72\x69\x67\x68\x74\x2d\x68\x61\x6e\x64\x2d\x72\x75\x6c\x65\x20" ++
"\x76\x65\x72\x74\x65\x78\x20\x77\x69\x6e\x64\x69\x6e\x67\x00\x00\x00\x00" ++
"\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x00\x00\x00\x00\x80\x3f\x00\x00" ++
"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00" ++
"\x00\x00\x00\x00\x00\x00\x80\x3f\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00" ++
"\x80\x3f\x00\x00\x80\x3f\x00\x00\x00\x00\x00\x00\xf3\x04\x35\xbf\xf3\x04" ++
"\x35\x3f\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x80\x3f" ++
"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x80\x3f\x00\x00\x80\x3f\x00\x00" ++
"\x80\x3f\x00\x00";
const allocator = std.testing.allocator;
var mesh = try Mesh.fromByteArray(binary_stl, allocator);
defer mesh.deinit(allocator);
try std.testing.expect(vec3.vec3ApproxEq(
mesh.vertices.items[0],
vec3.Vec3F64.init(0, 0, 0),
1e-12,
));
try std.testing.expect(vec3.vec3ApproxEq(
mesh.vertices.items[1],
vec3.Vec3F64.init(0, 1, 0),
1e-12,
));
try std.testing.expect(vec3.vec3ApproxEq(
mesh.vertices.items[2],
vec3.Vec3F64.init(0, 1, 1),
1e-12,
));
try std.testing.expect(vec3.vec3ApproxEq(
mesh.vertices.items[3],
vec3.Vec3F64.init(1, 0, 0),
1e-12,
));
try std.testing.expect(vec3.vec3ApproxEq(
mesh.vertices.items[4],
vec3.Vec3F64.init(1, 1, 1),
1e-12,
));
}