gvox-sys 1.3.0

Voxel file format parser
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226

#include <gvox/gvox.h>
#include <gvox/adapters/parse/gvox_palette.h>

#include "../shared/gvox_palette.hpp"

#include <cstdlib>
#include <cstdint>

#include <bit>
#include <vector>
#include <new>

struct GvoxPaletteParseUserState {
    GvoxRegionRange range{};
    uint32_t blob_size{};
    uint32_t channel_flags{};
    uint32_t channel_n{};

    size_t offset{};
    uint32_t r_nx{};
    uint32_t r_ny{};
    uint32_t r_nz{};

    std::vector<ChannelHeader> region_headers{};
    std::vector<uint8_t> buffer{};

    std::array<uint32_t, 32> channel_indices{};
};

// Base
extern "C" void gvox_parse_adapter_gvox_palette_create(GvoxAdapterContext *ctx, void const * /*unused*/) {
    auto *user_state_ptr = malloc(sizeof(GvoxPaletteParseUserState));
    new (user_state_ptr) GvoxPaletteParseUserState();
    gvox_adapter_set_user_pointer(ctx, user_state_ptr);
}

extern "C" void gvox_parse_adapter_gvox_palette_destroy(GvoxAdapterContext *ctx) {
    auto &user_state = *static_cast<GvoxPaletteParseUserState *>(gvox_adapter_get_user_pointer(ctx));
    user_state.~GvoxPaletteParseUserState();
    free(&user_state);
}

extern "C" void gvox_parse_adapter_gvox_palette_blit_begin(GvoxBlitContext *blit_ctx, GvoxAdapterContext *ctx, GvoxRegionRange const * /*unused*/, uint32_t /*unused*/) {
    auto &user_state = *static_cast<GvoxPaletteParseUserState *>(gvox_adapter_get_user_pointer(ctx));

    uint32_t magic = 0;
    gvox_input_read(blit_ctx, user_state.offset, sizeof(uint32_t), &magic);
    user_state.offset += sizeof(uint32_t);

    if (magic != std::bit_cast<uint32_t>(std::array<char, 4>{'g', 'v', 'p', '\0'})) {
        gvox_adapter_push_error(ctx, GVOX_RESULT_ERROR_PARSE_ADAPTER_INVALID_INPUT, "parsing a gvox palette format must begin with a valid magic number");
        return;
    }

    gvox_input_read(blit_ctx, user_state.offset, sizeof(GvoxRegionRange), &user_state.range);
    user_state.offset += sizeof(GvoxRegionRange);

    gvox_input_read(blit_ctx, user_state.offset, sizeof(uint32_t), &user_state.blob_size);
    user_state.offset += sizeof(uint32_t);

    gvox_input_read(blit_ctx, user_state.offset, sizeof(uint32_t), &user_state.channel_flags);
    user_state.offset += sizeof(uint32_t);

    gvox_input_read(blit_ctx, user_state.offset, sizeof(uint32_t), &user_state.channel_n);
    user_state.offset += sizeof(uint32_t);

    uint32_t next_channel = 0;
    for (uint8_t channel_i = 0; channel_i < 32; ++channel_i) {
        if ((user_state.channel_flags & (1u << channel_i)) != 0) {
            user_state.channel_indices[channel_i] = next_channel;
            ++next_channel;
        }
    }

    user_state.r_nx = (user_state.range.extent.x + REGION_SIZE - 1) / REGION_SIZE;
    user_state.r_ny = (user_state.range.extent.y + REGION_SIZE - 1) / REGION_SIZE;
    user_state.r_nz = (user_state.range.extent.z + REGION_SIZE - 1) / REGION_SIZE;

    user_state.region_headers.resize(static_cast<size_t>(user_state.r_nx) * user_state.r_ny * user_state.r_nz * user_state.channel_n);
    for (auto &region_header : user_state.region_headers) {
        gvox_input_read(blit_ctx, user_state.offset, sizeof(ChannelHeader), &region_header);
        user_state.offset += sizeof(ChannelHeader);
    }

    user_state.buffer.resize(user_state.blob_size);
    gvox_input_read(blit_ctx, user_state.offset, user_state.blob_size, user_state.buffer.data());
}

extern "C" void gvox_parse_adapter_gvox_palette_blit_end(GvoxBlitContext * /*unused*/, GvoxAdapterContext * /*unused*/) {
}

// General
extern "C" auto gvox_parse_adapter_gvox_palette_query_details() -> GvoxParseAdapterDetails {
    return {
        .preferred_blit_mode = GVOX_BLIT_MODE_DONT_CARE,
    };
}

extern "C" auto gvox_parse_adapter_gvox_palette_query_parsable_range(GvoxBlitContext * /*unused*/, GvoxAdapterContext *ctx) -> GvoxRegionRange {
    auto &user_state = *static_cast<GvoxPaletteParseUserState *>(gvox_adapter_get_user_pointer(ctx));
    return user_state.range;
}

extern "C" auto gvox_parse_adapter_gvox_palette_sample_region(GvoxBlitContext * /*unused*/, GvoxAdapterContext *ctx, GvoxRegion const * /*unused*/, GvoxOffset3D const *offset, uint32_t channel_id) -> GvoxSample {
    auto &user_state = *static_cast<GvoxPaletteParseUserState *>(gvox_adapter_get_user_pointer(ctx));
    if (offset->x < user_state.range.offset.x ||
        offset->y < user_state.range.offset.y ||
        offset->z < user_state.range.offset.z ||
        offset->x >= user_state.range.offset.x + static_cast<int32_t>(user_state.range.extent.x) ||
        offset->y >= user_state.range.offset.y + static_cast<int32_t>(user_state.range.extent.y) ||
        offset->z >= user_state.range.offset.z + static_cast<int32_t>(user_state.range.extent.z)) {
        return {0u, 0u};
    }
    auto const xi = static_cast<uint32_t>(offset->x - user_state.range.offset.x) / REGION_SIZE;
    auto const yi = static_cast<uint32_t>(offset->y - user_state.range.offset.y) / REGION_SIZE;
    auto const zi = static_cast<uint32_t>(offset->z - user_state.range.offset.z) / REGION_SIZE;
    auto const px = static_cast<uint32_t>(offset->x - user_state.range.offset.x) - xi * REGION_SIZE;
    auto const py = static_cast<uint32_t>(offset->y - user_state.range.offset.y) - yi * REGION_SIZE;
    auto const pz = static_cast<uint32_t>(offset->z - user_state.range.offset.z) - zi * REGION_SIZE;
    auto r_nx = user_state.r_nx;
    auto r_ny = user_state.r_ny;
    auto &channel_header = user_state.region_headers[user_state.channel_indices[channel_id] + (xi + yi * r_nx + zi * r_nx * r_ny) * user_state.channel_n];
    if (channel_header.variant_n <= 1) {
        return {channel_header.blob_offset, 1u};
    } else {
        uint8_t *buffer_ptr = user_state.buffer.data() + channel_header.blob_offset;
        if (channel_header.variant_n > MAX_REGION_COMPRESSED_VARIANT_N) {
            auto const index = px + py * REGION_SIZE + pz * REGION_SIZE * REGION_SIZE;
            // return 0;
            return {*reinterpret_cast<uint32_t *>(buffer_ptr + index * sizeof(uint32_t)), 1u};
        } else {
            auto *palette_begin = reinterpret_cast<uint32_t *>(buffer_ptr);
            auto const bits_per_variant = ceil_log2(channel_header.variant_n);
            buffer_ptr += channel_header.variant_n * sizeof(uint32_t);
            auto const index = px + py * REGION_SIZE + pz * REGION_SIZE * REGION_SIZE;
            auto const bit_index = static_cast<uint32_t>(index) * bits_per_variant;
            auto const byte_index = bit_index / 8;
            auto const bit_offset = static_cast<uint32_t>(bit_index - byte_index * 8);
            auto const mask = get_mask(bits_per_variant);
#if 0
            // Note: This is technically UB, since I think it breaks the strict aliasing rules of C++.
            auto input = *reinterpret_cast<uint32_t *>(buffer_ptr + byte_index);
            // The "correct" solution is below.
#else
            auto input = std::bit_cast<uint32_t>(*reinterpret_cast<std::array<uint8_t, 4> *>(buffer_ptr + byte_index));
#endif
            auto const palette_id = (input >> bit_offset) & mask;
            // return palette_id;
            return {palette_begin[palette_id], 1u};
        }
    }
}

// Serialize Driven
extern "C" auto gvox_parse_adapter_gvox_palette_query_region_flags(GvoxBlitContext * /*unused*/, GvoxAdapterContext *ctx, GvoxRegionRange const *range, uint32_t channel_flags) -> uint32_t {
    auto &user_state = *static_cast<GvoxPaletteParseUserState *>(gvox_adapter_get_user_pointer(ctx));

    if ((channel_flags & ~user_state.channel_flags) != 0) {
        gvox_adapter_push_error(ctx, GVOX_RESULT_ERROR_PARSE_ADAPTER_REQUESTED_CHANNEL_NOT_PRESENT, "Tried loading a region with a channel that wasn't present in the original data");
        return 0;
    }

    auto ax = static_cast<uint32_t>(range->offset.x - user_state.range.offset.x) / static_cast<uint32_t>(REGION_SIZE);
    auto ay = static_cast<uint32_t>(range->offset.y - user_state.range.offset.y) / static_cast<uint32_t>(REGION_SIZE);
    auto az = static_cast<uint32_t>(range->offset.z - user_state.range.offset.z) / static_cast<uint32_t>(REGION_SIZE);
    auto bx = (static_cast<uint32_t>(range->offset.x - user_state.range.offset.x) + range->extent.x + static_cast<uint32_t>(REGION_SIZE - 1)) / static_cast<uint32_t>(REGION_SIZE);
    auto by = (static_cast<uint32_t>(range->offset.y - user_state.range.offset.y) + range->extent.y + static_cast<uint32_t>(REGION_SIZE - 1)) / static_cast<uint32_t>(REGION_SIZE);
    auto bz = (static_cast<uint32_t>(range->offset.z - user_state.range.offset.z) + range->extent.z + static_cast<uint32_t>(REGION_SIZE - 1)) / static_cast<uint32_t>(REGION_SIZE);

    uint32_t flags = 0;

    for (uint32_t channel_id = 0; channel_id < 32; ++channel_id) {
        if (((1u << channel_id) & channel_flags) != 0) {
            auto channel_index = user_state.channel_indices[channel_id];
            auto &a_channel_header = user_state.region_headers[channel_index + (ax + ay * user_state.r_nx + az * user_state.r_nx * user_state.r_ny) * user_state.channel_n];
            if (a_channel_header.variant_n == 1) {
                flags |= GVOX_REGION_FLAG_UNIFORM;
                for (uint32_t zi = az; zi < bz; ++zi) {
                    for (uint32_t yi = ay; yi < by; ++yi) {
                        for (uint32_t xi = ax; xi < bx; ++xi) {
                            auto &b_channel_header = user_state.region_headers[channel_index + (xi + yi * user_state.r_nx + zi * user_state.r_nx * user_state.r_ny) + user_state.channel_n];
                            if (b_channel_header.variant_n != 1 || b_channel_header.blob_offset != a_channel_header.blob_offset) {
                                flags = 0;
                                break;
                            }
                        }
                    }
                }
            }
        }
    }

    return flags;
}

extern "C" auto gvox_parse_adapter_gvox_palette_load_region(GvoxBlitContext * /*unused*/, GvoxAdapterContext *ctx, GvoxRegionRange const *range, uint32_t channel_flags) -> GvoxRegion {
    auto &user_state = *static_cast<GvoxPaletteParseUserState *>(gvox_adapter_get_user_pointer(ctx));
    if ((channel_flags & ~user_state.channel_flags) != 0) {
        gvox_adapter_push_error(ctx, GVOX_RESULT_ERROR_PARSE_ADAPTER_REQUESTED_CHANNEL_NOT_PRESENT, "Tried loading a region with a channel that wasn't present in the original data");
    }
    GvoxRegion const region = {
        .range = *range,
        .channels = channel_flags & user_state.channel_flags,
        .flags = 0u,
        .data = nullptr,
    };
    return region;
}

extern "C" void gvox_parse_adapter_gvox_palette_unload_region(GvoxBlitContext * /*unused*/, GvoxAdapterContext * /*unused*/, GvoxRegion * /*unused*/) {
}

// Parse Driven
extern "C" void gvox_parse_adapter_gvox_palette_parse_region(GvoxBlitContext *blit_ctx, GvoxAdapterContext *ctx, GvoxRegionRange const *range, uint32_t channel_flags) {
    auto &user_state = *static_cast<GvoxPaletteParseUserState *>(gvox_adapter_get_user_pointer(ctx));
    if ((channel_flags & ~user_state.channel_flags) != 0) {
        gvox_adapter_push_error(ctx, GVOX_RESULT_ERROR_PARSE_ADAPTER_REQUESTED_CHANNEL_NOT_PRESENT, "Tried loading a region with a channel that wasn't present in the original data");
    }
    GvoxRegion const region = {
        .range = *range,
        .channels = channel_flags & user_state.channel_flags,
        .flags = 0u,
        .data = nullptr,
    };
    gvox_emit_region(blit_ctx, &region);
}