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const std = @import("std");
const mesh = @import("mesh.zig");
const Allocator = std.mem.Allocator;
pub const Model = struct {
const Asset = struct {
version: []u8,
generator: ?[]u8 = null,
copyright: ?[]u8 = null,
};
const Buffer = struct {
byteLength: usize,
uri: ?[]u8 = null,
};
const BufferView = struct {
buffer: usize,
byteLength: usize,
byteOffset: usize,
byteStride: ?usize = null,
target: ?usize = null,
};
const Node = struct {
name: []u8,
mesh: ?usize = null,
weights: ?[]f64 = null,
children: ?[]usize = null,
rotation: ?[4]f64 = null,
scale: ?[3]f64 = null,
translation: ?[3]f64 = null,
camera: ?usize = null,
matrix: ?[16]usize = null,
};
const Accessor = struct {
bufferView: usize,
byteOffset: ?usize = null,
componentType: usize,
count: usize,
type: []u8,
max: ?[]f64 = null,
min: ?[]f64 = null,
};
const Primitive = struct {
const Attributes = struct {
NORMAL: ?usize = null,
POSITION: ?usize = null,
TANGENT: ?usize = null,
TEXCOORD_0: ?usize = null,
TEXCOORD_1: ?usize = null,
COLOR_0: ?usize = null,
JOINTS_0: ?usize = null,
WEIGHTS_0: ?usize = null,
};
attributes: ?Attributes = null,
indices: ?usize = null,
material: ?usize = null,
mode: ?usize = null,
};
const Mesh = struct {
name: ?[]u8 = null,
primitives: ?[]Primitive = null,
weights: ?[]f64 = null,
};
const Skin = struct {
inverseBindMatrices: usize,
joints: []usize,
skeleton: usize,
};
const Texture = struct {
sampler: usize,
source: usize,
};
const Image = struct {
uri: ?[]u8 = null,
bufferView: ?usize = null,
mimeType: ?[]u8 = null,
};
const Material = struct {
const Pbr = struct {
baseColorFactor: ?[4]f64 = null,
baseColorTexture: ?struct {
index: usize,
texCoord: usize,
} = null,
metallicFactor: ?f64 = null,
roughnessFactor: ?f64 = null,
};
name: ?[]u8 = null,
pbrMetallicRoughness: Pbr,
doubleSided: bool,
};
const Scene = struct {
nodes: ?[]usize = null,
name: ?[]u8 = null,
};
const Chunk = packed struct {
const offset = Header.offset + 8;
length: u32,
type: u32,
};
const JsonChunk = struct {
asset: Asset,
scene: usize,
scenes: ?[]Scene = null,
nodes: ?[]Node = null,
materials: ?[]Material = null,
meshes: ?[]Mesh = null,
accessors: ?[]Accessor = null,
bufferViews: ?[]BufferView = null,
buffers: ?[]Buffer = null,
};
const Header = packed struct {
const offset = 12;
magic: u32,
version: u32,
length: u32,
};
const Binary = struct {
data: []u8,
const Vec3 = [3]f32;
pub fn readU16(self: Binary, allocator: Allocator, view: BufferView, count: usize) ![]u16 {
const data = self.data[view.byteOffset .. view.byteOffset + view.byteLength];
const scalars = try allocator.alloc(u16, count);
var j: usize = 0;
for (0..data.len / 2) |i| {
scalars[i] = std.mem.bytesAsValue(u16, data[j .. j + 1]).*;
j += 2;
}
return scalars;
}
pub fn readVec3(self: Binary, allocator: Allocator, view: BufferView, count: usize) ![]Vec3 {
const data = self.data[view.byteOffset .. view.byteOffset + view.byteLength];
const vectors = try allocator.alloc(Vec3, count);
for (0..count) |i| {
vectors[i] = std.mem.bytesAsValue(Vec3, data[(@sizeOf(Vec3) * i) .. (@sizeOf(Vec3) * i) + @sizeOf(Vec3)]).*;
}
return vectors;
}
};
};
pub fn parseFile(allocator: Allocator, name: []const u8) !struct { vertices: [][3]f32, indices: []u16 } {
const file = try std.fs.cwd().openFile(name, .{});
const all = try file.readToEndAlloc(allocator, 1_000_000);
const json_chunk = std.mem.bytesAsValue(Model.Chunk, all[Model.Header.offset..]);
const data = (try std.json.parseFromSlice(Model.JsonChunk, allocator, @constCast(all[Model.Chunk.offset .. Model.Chunk.offset + json_chunk.length]), .{ .ignore_unknown_fields = true })).value;
const binary = Model.Binary{ .data = all[Model.Chunk.offset + json_chunk.length + 8 ..] };
const vertices = try binary.readVec3(allocator, data.bufferViews.?[data.meshes.?[0].primitives.?[0].attributes.?.POSITION.?], 24);
const indices = try binary.readU16(allocator, data.bufferViews.?[data.meshes.?[0].primitives.?[0].indices.?], 36);
std.debug.print("vertices: {any}\n", .{vertices});
std.debug.print("indices: {any}\n", .{indices});
return .{ .vertices = vertices, .indices = indices };
}
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