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support sparse accessors (untested)
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@skyfloogle
skyfloogle committed Aug 23, 2024
1 parent acabcc3 commit 2e63d19
Showing 1 changed file with 84 additions and 13 deletions.
97 changes: 84 additions & 13 deletions src/root.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -16,11 +16,12 @@ var g_gltfs = std.AutoArrayHashMap(i32, GLB).init(g_allocator.allocator());
var g_gltf_next_id: i32 = 1;
var g_stringret: ?[:0]u8 = null;
var g_matrices = std.ArrayList([16]f32).init(g_allocator.allocator());
var g_data: ?[]u8 = null;

fn return_string(string: []const u8) [*:0]const u8 {
// make new string
const new_string = g_allocator.allocator().allocSentinel(u8, string.len, 0) catch return "";
std.mem.copyForwards(u8, new_string, string);
@memcpy(new_string, string);
// replace with new string
if (g_stringret) |stringret| {
g_allocator.allocator().free(stringret);
Expand Down Expand Up @@ -181,6 +182,33 @@ fn create_full_transform(gltf: *const GLTF, node_id: usize, skeleton: ?usize) [1
return matrix;
}

fn component_type_size(component_type: usize) usize {
return switch (component_type) {
5120 => 1,
5121 => 1,
5122 => 2,
5123 => 2,
5125 => 4,
5126 => 4,
else => 0,
};
}

fn type_count(t: []const u8) usize {
if (std.mem.eql(u8, t, "SCALAR")) return 1;
if (std.mem.eql(u8, t, "VEC2")) return 2;
if (std.mem.eql(u8, t, "VEC3")) return 3;
if (std.mem.eql(u8, t, "VEC4")) return 4;
if (std.mem.eql(u8, t, "MAT2")) return 4;
if (std.mem.eql(u8, t, "MAT3")) return 9;
if (std.mem.eql(u8, t, "MAT4")) return 16;
return 0;
}

fn accessor_stride(accessor: *const GLTF.Accessor) usize {
return component_type_size(accessor.componentType) * type_count(accessor.type);
}

// EXPORTS

export fn __gltf_reset() f64 {
Expand Down Expand Up @@ -779,8 +807,8 @@ export fn gltf_accessor_stride(gltf_id: f64, accessor_id: f64) f64 {
const glb = get_glb(gltf_id) orelse return -1;
const gltf = &glb.json.value;
const accessor = array_get(GLTF.Accessor, gltf.accessors, accessor_id) orelse return -1;
const bv = array_get(GLTF.BufferView, gltf.bufferViews, accessor.bufferView) orelse return -1;
return @floatFromInt(bv.byteStride orelse return -1);
const bv = array_get(GLTF.BufferView, gltf.bufferViews, accessor.bufferView) orelse return @floatFromInt(accessor_stride(accessor));
return @floatFromInt(bv.byteStride orelse accessor_stride(accessor));
}

export fn gltf_accessor_copy(gltf_id: f64, accessor_id: f64, dest_address: f64, dest_size: f64) f64 {
Expand All @@ -792,31 +820,74 @@ export fn gltf_accessor_copy(gltf_id: f64, accessor_id: f64, dest_address: f64,
const accessor = array_get(GLTF.Accessor, gltf.accessors, accessor_id) orelse return -1;
const bv = array_get(GLTF.BufferView, gltf.bufferViews, accessor.bufferView) orelse return -1;
const buffer = array_get([]const u8, glb.buffers, bv.buffer) orelse return -1;
// TODO copy accessor instead of buffer view
const data = buffer.*[bv.byteOffset .. bv.byteOffset + bv.byteLength];
const offset = bv.byteOffset + accessor.byteOffset;
const size = (bv.byteStride orelse accessor_stride(accessor)) * accessor.count;
const data = buffer.*[offset .. offset + size];
if (dest.len != data.len) {
return -1;
}
std.mem.copyForwards(u8, dest, data);
@memcpy(dest, data);
return 0;
}

export fn gltf_accessor_pointer(gltf_id: f64, accessor_id: f64) f64 {
const glb = get_glb(gltf_id) orelse return -1;
const gltf = &glb.json.value;
const accessor = array_get(GLTF.Accessor, gltf.accessors, accessor_id) orelse return -1;
const bv = array_get(GLTF.BufferView, gltf.bufferViews, accessor.bufferView) orelse return -1;
const data = array_get([]const u8, glb.buffers, bv.buffer) orelse return -1;
return @floatFromInt(@intFromPtr(data.ptr) + bv.byteOffset + accessor.byteOffset);
if (accessor.sparse) |sparse| {
const bv_maybe = array_get(GLTF.BufferView, gltf.bufferViews, accessor.bufferView);
const packed_stride = accessor_stride(accessor);
var stride = packed_stride;
if (bv_maybe) |bv| {
if (bv.byteStride) |s| stride = s;
}
const size = accessor.count * stride;
if (g_data) |data| g_allocator.allocator().free(data);
const data = g_allocator.allocator().alignedAlloc(u8, 4, size) catch return -1;
g_data = data;
if (bv_maybe) |bv| {
const buffer = array_get([]const u8, glb.buffers, bv.buffer) orelse return -1;
const offset = bv.byteOffset + accessor.byteOffset;
@memcpy(data, @as([*]const u8, @ptrCast(buffer.ptr))[offset .. offset + size]);
} else {
@memset(data, 0);
}
const indices_bv = array_get(GLTF.BufferView, gltf.bufferViews, sparse.indices.bufferView) orelse return -1;
const indices_data: []align(4) const u8 = blk: {
const buffer = array_get([]align(4) const u8, glb.buffers, indices_bv.buffer) orelse return -1;
const offset = indices_bv.byteOffset + sparse.indices.byteOffset;
break :blk @alignCast(buffer.*[offset..]);
};
const values_bv = array_get(GLTF.BufferView, gltf.bufferViews, sparse.values.bufferView) orelse return -1;
const values_data = blk: {
const buffer = array_get([]const u8, glb.buffers, values_bv.buffer) orelse return -1;
const offset = values_bv.byteOffset + sparse.values.byteOffset;
break :blk buffer.*[offset..];
};
for (0..sparse.count) |i| {
const index = switch (sparse.indices.componentType) {
5121 => indices_data[i],
5123 => @as([*]const u16, @ptrCast(indices_data.ptr))[i],
5125 => @as([*]const u32, @ptrCast(indices_data.ptr))[i],
else => return -1,
};
@memcpy(data[stride * index .. stride * (index + 1)], values_data[packed_stride * i .. packed_stride * (i + 1)]);
}
return @floatFromInt(@intFromPtr(data.ptr));
} else {
const bv = array_get(GLTF.BufferView, gltf.bufferViews, accessor.bufferView) orelse return -1;
const data = array_get([]const u8, glb.buffers, bv.buffer) orelse return -1;
return @floatFromInt(@intFromPtr(data.ptr) + bv.byteOffset + accessor.byteOffset);
}
}

export fn gltf_accessor_size(gltf_id: f64, accessor_id: f64) f64 {
const glb = get_glb(gltf_id) orelse return -1;
const gltf = &glb.json.value;
const accessor = array_get(GLTF.Accessor, gltf.accessors, accessor_id) orelse return -1;
const bv = array_get(GLTF.BufferView, gltf.bufferViews, accessor.bufferView) orelse return -1;
// TODO calculate using accessor type and such, this is incorrect
return @floatFromInt(bv.byteLength);
const bv = array_get(GLTF.BufferView, gltf.bufferViews, accessor.bufferView) orelse return @floatFromInt(accessor.count * accessor_stride(accessor));
const stride = bv.byteStride orelse accessor_stride(accessor);
return @floatFromInt(accessor.count * stride);
}

export fn gltf_material_base_texture(gltf_id: f64, material_id: f64) f64 {
Expand Down Expand Up @@ -958,7 +1029,7 @@ export fn gltf_texture_copy(gltf_id: f64, texture_id: f64, dest_address: f64, de
if (dest.len != data.len) {
return -1;
}
std.mem.copyForwards(u8, dest, data);
@memcpy(dest, data);
return 0;
}

Expand Down

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