Martin Michelsen
119 lines
3.4 KiB
C++
119 lines
3.4 KiB
C++
#include "GVMEncoder.hh"
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#include <phosg/Encoding.hh>
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#include <phosg/Image.hh>
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#include <phosg/Strings.hh>
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#include "Text.hh"
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using namespace std;
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static uint16_t encode_rgb565(uint8_t r, uint8_t g, uint8_t b) {
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return ((r << 8) & 0xF800) | ((g << 3) & 0x07E0) | ((b >> 3) & 0x001F);
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}
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static uint16_t encode_rgb5a3(uint8_t r, uint8_t g, uint8_t b, uint8_t a) {
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if ((a & 0xE0) == 0xE0) {
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return 0x8000 | ((r << 7) & 0x7C00) | ((g << 2) & 0x03E0) | ((b >> 3) & 0x001F);
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} else {
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return ((a << 7) & 0x7000) | ((r << 4) & 0x0F00) | (g & 0x00F0) | ((b >> 4) & 0x000F);
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}
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}
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static uint32_t encode_argb8888(uint8_t r, uint8_t g, uint8_t b, uint8_t a) {
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return (a << 24) | (r << 16) | (g << 8) | b;
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}
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struct GVMFileEntry {
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be_uint16_t file_num;
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ptext<char, 28> name;
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parray<be_uint32_t, 2> unknown_a1;
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} __attribute__((packed));
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struct GVMFileHeader {
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be_uint32_t magic; // 'GVMH'
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le_uint32_t header_size;
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be_uint16_t flags;
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be_uint16_t num_files;
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} __attribute__((packed));
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struct GVRHeader {
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be_uint32_t magic; // 'GVRT'
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le_uint32_t data_size;
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be_uint16_t unknown;
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uint8_t format_flags; // High 4 bits are pixel format, low 4 are data flags
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GVRDataFormat data_format;
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be_uint16_t width;
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be_uint16_t height;
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} __attribute__((packed));
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string encode_gvm(const Image& img, GVRDataFormat data_format) {
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if (img.get_width() > 0xFFFF) {
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throw runtime_error("image is too wide to be encoded as a GVR texture");
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}
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if (img.get_height() > 0xFFFF) {
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throw runtime_error("image is too tall to be encoded as a GVR texture");
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}
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if (img.get_width() & 3) {
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throw runtime_error("image width is not a multiple of 4");
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}
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if (img.get_height() & 3) {
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throw runtime_error("image height is not a multiple of 4");
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}
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size_t pixel_count = img.get_width() * img.get_height();
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size_t pixel_bytes = 0;
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switch (data_format) {
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case GVRDataFormat::RGB565:
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case GVRDataFormat::RGB5A3:
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pixel_bytes = pixel_count * 2;
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break;
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case GVRDataFormat::ARGB8888:
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pixel_bytes = pixel_count * 2;
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break;
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default:
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throw invalid_argument("cannot encode pixel format");
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}
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StringWriter w;
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w.put<GVMFileHeader>({.magic = 0x47564D48, .header_size = 0x48, .flags = 0x010F, .num_files = 1});
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GVMFileEntry file_entry;
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file_entry.file_num = 0;
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file_entry.name = "img";
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file_entry.unknown_a1.clear(0);
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w.put(file_entry);
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w.extend_to(0x50, 0x00);
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w.put<GVRHeader>({.magic = 0x47565254,
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.data_size = pixel_bytes + 8,
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.unknown = 0,
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.format_flags = 0,
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.data_format = data_format,
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.width = img.get_width(),
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.height = img.get_height()});
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for (size_t y = 0; y < img.get_height(); y += 4) {
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for (size_t x = 0; x < img.get_width(); x += 4) {
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for (size_t yy = 0; yy < 4; yy++) {
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for (size_t xx = 0; xx < 4; xx++) {
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uint64_t a, r, g, b;
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img.read_pixel(x + xx, y + yy, &r, &g, &b, &a);
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switch (data_format) {
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case GVRDataFormat::RGB565:
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w.put_u16b(encode_rgb565(r, g, b));
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break;
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case GVRDataFormat::RGB5A3:
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w.put_u16b(encode_rgb5a3(r, g, b, a));
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break;
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case GVRDataFormat::ARGB8888:
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w.put_u32b(encode_argb8888(r, g, b, a));
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break;
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default:
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throw logic_error("cannot encode pixel format");
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}
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}
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}
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}
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}
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return std::move(w.str());
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}
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