Add S3TC support to imageio and Suzanne.
At build time, mipgen now creates several compressed and non-compressed variants for albedo. For ASTC we use the ARM encoder, for S3TC we use the STB encoder. The latter is somewhat limited so we may wish to investigate other libraries in the future (e.g., AMD Compressenator). At run time, we detect which of these variants to download, based on available WebGL extensions. In practice, this means that desktop browsers will use the S3TC variant and mobile browsers will use the ASTC variant. The makes unzipped albedo go from ~4 MB to 682 KB using S3TC. Mobile support (ASTC and ETC2) is coming in a future PR, stay tuned.
This commit is contained in:
Philip Rideout
@@ -22,13 +22,18 @@
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#include <astcenc.h>
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#define STB_DXT_IMPLEMENTATION
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#include <stb_dxt.h>
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using namespace image;
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using std::string;
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namespace image {
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AstcTexture astcCompress(const LinearImage& original, AstcConfig config) {
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static LinearImage extendToFourChannels(LinearImage source);
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CompressedTexture astcCompress(const LinearImage& original, AstcConfig config) {
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// If this is the first time, initialize the ARM encoder tables.
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@@ -42,35 +47,36 @@ AstcTexture astcCompress(const LinearImage& original, AstcConfig config) {
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// Check the validity of the given block size.
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AstcFormat format;
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using Format = CompressedFormat;
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Format format;
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if (config.blocksize == math::ushort2 {4, 4}) {
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format = config.srgb ? AstcFormat::SRGB8_ALPHA8_ASTC_4x4 : AstcFormat::RGBA_ASTC_4x4;
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format = config.srgb ? Format::SRGB8_ALPHA8_ASTC_4x4 : Format::RGBA_ASTC_4x4;
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} else if (config.blocksize == math::ushort2 {5, 4}) {
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format = config.srgb ? AstcFormat::SRGB8_ALPHA8_ASTC_5x4 : AstcFormat::RGBA_ASTC_5x4;
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format = config.srgb ? Format::SRGB8_ALPHA8_ASTC_5x4 : Format::RGBA_ASTC_5x4;
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} else if (config.blocksize == math::ushort2 {5, 5}) {
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format = config.srgb ? AstcFormat::SRGB8_ALPHA8_ASTC_5x5 : AstcFormat::RGBA_ASTC_5x5;
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format = config.srgb ? Format::SRGB8_ALPHA8_ASTC_5x5 : Format::RGBA_ASTC_5x5;
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} else if (config.blocksize == math::ushort2 {6, 5}) {
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format = config.srgb ? AstcFormat::SRGB8_ALPHA8_ASTC_6x5 : AstcFormat::RGBA_ASTC_6x5;
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format = config.srgb ? Format::SRGB8_ALPHA8_ASTC_6x5 : Format::RGBA_ASTC_6x5;
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} else if (config.blocksize == math::ushort2 {6, 6}) {
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format = config.srgb ? AstcFormat::SRGB8_ALPHA8_ASTC_6x6 : AstcFormat::RGBA_ASTC_6x6;
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format = config.srgb ? Format::SRGB8_ALPHA8_ASTC_6x6 : Format::RGBA_ASTC_6x6;
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} else if (config.blocksize == math::ushort2 {8, 5}) {
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format = config.srgb ? AstcFormat::SRGB8_ALPHA8_ASTC_8x5 : AstcFormat::RGBA_ASTC_8x5;
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format = config.srgb ? Format::SRGB8_ALPHA8_ASTC_8x5 : Format::RGBA_ASTC_8x5;
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} else if (config.blocksize == math::ushort2 {8, 6}) {
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format = config.srgb ? AstcFormat::SRGB8_ALPHA8_ASTC_8x6 : AstcFormat::RGBA_ASTC_8x6;
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format = config.srgb ? Format::SRGB8_ALPHA8_ASTC_8x6 : Format::RGBA_ASTC_8x6;
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} else if (config.blocksize == math::ushort2 {8, 8}) {
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format = config.srgb ? AstcFormat::SRGB8_ALPHA8_ASTC_8x8 : AstcFormat::RGBA_ASTC_8x8;
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format = config.srgb ? Format::SRGB8_ALPHA8_ASTC_8x8 : Format::RGBA_ASTC_8x8;
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} else if (config.blocksize == math::ushort2 {10, 5}) {
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format = config.srgb ? AstcFormat::SRGB8_ALPHA8_ASTC_10x5 : AstcFormat::RGBA_ASTC_10x5;
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format = config.srgb ? Format::SRGB8_ALPHA8_ASTC_10x5 : Format::RGBA_ASTC_10x5;
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} else if (config.blocksize == math::ushort2 {10, 6}) {
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format = config.srgb ? AstcFormat::SRGB8_ALPHA8_ASTC_10x6 : AstcFormat::RGBA_ASTC_10x6;
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format = config.srgb ? Format::SRGB8_ALPHA8_ASTC_10x6 : Format::RGBA_ASTC_10x6;
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} else if (config.blocksize == math::ushort2 {10, 8}) {
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format = config.srgb ? AstcFormat::SRGB8_ALPHA8_ASTC_10x8 : AstcFormat::RGBA_ASTC_10x8;
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format = config.srgb ? Format::SRGB8_ALPHA8_ASTC_10x8 : Format::RGBA_ASTC_10x8;
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} else if (config.blocksize == math::ushort2 {10, 10}) {
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format = config.srgb ? AstcFormat::SRGB8_ALPHA8_ASTC_10x10 : AstcFormat::RGBA_ASTC_10x10;
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format = config.srgb ? Format::SRGB8_ALPHA8_ASTC_10x10 : Format::RGBA_ASTC_10x10;
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} else if (config.blocksize == math::ushort2 {12, 10}) {
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format = config.srgb ? AstcFormat::SRGB8_ALPHA8_ASTC_12x10 : AstcFormat::RGBA_ASTC_12x10;
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format = config.srgb ? Format::SRGB8_ALPHA8_ASTC_12x10 : Format::RGBA_ASTC_12x10;
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} else if (config.blocksize == math::ushort2 {12, 12}) {
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format = config.srgb ? AstcFormat::SRGB8_ALPHA8_ASTC_12x12 : AstcFormat::RGBA_ASTC_12x12;
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format = config.srgb ? Format::SRGB8_ALPHA8_ASTC_12x12 : Format::RGBA_ASTC_12x12;
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} else {
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return {};
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}
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@@ -79,43 +85,9 @@ AstcTexture astcCompress(const LinearImage& original, AstcConfig config) {
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// It expects four-channel data, so we extend or curtail the channel count in a reasonable way.
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// The encoder can take half-floats or bytes, but we always give it half-floats.
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LinearImage source = original;
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LinearImage source = extendToFourChannels(original);
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const uint32_t width = source.getWidth();
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const uint32_t height = source.getHeight();
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auto createEmptyImage = [width, height](float value) {
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auto result = LinearImage(width, height, 1);
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float* pixels = result.getPixelRef(0, 0);
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std::fill(pixels, pixels + width * height, value);
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return result;
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};
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switch (source.getChannels()) {
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case 4: break;
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case 1: {
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auto l = image::extractChannel(source, 0);
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auto a = createEmptyImage(1.0f);
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source = image::combineChannels({l, l, l, a});
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}
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case 2: {
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auto l = image::extractChannel(source, 0);
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auto a = image::extractChannel(source, 1);
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source = image::combineChannels({l, l, l, a});
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}
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case 3: {
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auto r = image::extractChannel(source, 0);
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auto g = image::extractChannel(source, 1);
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auto b = image::extractChannel(source, 2);
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auto a = createEmptyImage(1.0f);
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source = image::combineChannels({r, g, b, a});
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}
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default: {
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auto r = image::extractChannel(source, 0);
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auto g = image::extractChannel(source, 1);
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auto b = image::extractChannel(source, 2);
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auto a = image::extractChannel(source, 3);
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source = image::combineChannels({r, g, b, a});
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}
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}
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astc_codec_image* input_image = allocate_image(16, width, height, 1, 0);
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for (int y = 0; y < height; y++) {
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auto imagedata16 = input_image->imagedata16[0][y];
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@@ -236,7 +208,7 @@ AstcTexture astcCompress(const LinearImage& original, AstcConfig config) {
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return {
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.format = format,
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.size = size,
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.data = decltype(AstcTexture::data)(buffer)
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.data = decltype(CompressedTexture::data)(buffer)
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};
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}
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@@ -282,4 +254,104 @@ AstcConfig astcParseOptionString(const string& configString) {
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return config;
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}
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static uint32_t imin(uint32_t a, uint32_t b) {
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return (a < b) ? a : b;
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}
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static void extract4x4RGBA(uint8_t* dst, const LinearImage& source, uint32_t x0, uint32_t y0) {
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const uint32_t maxx = source.getWidth() - 1;
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const uint32_t maxy = source.getHeight() - 1;
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for (uint32_t y = y0, y1 = y0 + 4; y < y1; ++y) {
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for (uint32_t x = x0, x1 = x0 + 4; x < x1; ++x, dst += 4) {
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int clamped_x = imin(maxx, x);
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int clamped_y = imin(maxy, y);
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float const* rgba = source.getPixelRef(clamped_x, clamped_y);
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dst[0] = (uint8_t) (rgba[0] * 255.0f);
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dst[1] = (uint8_t) (rgba[1] * 255.0f);
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dst[2] = (uint8_t) (rgba[2] * 255.0f);
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dst[3] = (uint8_t) (rgba[3] * 255.0f);
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}
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}
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}
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// Our S3TC / DXT encoder uses the STB implementation by Fabian Giesen.
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//
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// Due to limitations in STB, this only supports the following formats:
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// - DXT1 with no alpha (16 input pixels in 64 bits of output, 6:1)
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// - DXT5 with alpha (16 input pixels into 128 bits of output, 4:1)
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//
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// TODO: investigate using something more capable than STB (eg AMD Compressenator, bimg, libsquish)
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CompressedTexture s3tcCompress(const LinearImage& original, S3tcConfig config) {
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const bool dxt5 = config.format == CompressedFormat::RGBA_S3TC_DXT5;
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LinearImage source = extendToFourChannels(original);
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uint8_t block[64];
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uint32_t xblocks = (source.getWidth() + 3) / 4;
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uint32_t yblocks = (source.getHeight() + 3) / 4;
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uint32_t size = xblocks * yblocks * (dxt5 ? 16 : 8);
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uint8_t* buffer = new uint8_t[size];
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uint8_t* dst = buffer;
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for (int y = 0, h = source.getHeight(); y < h; y += 4) {
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for (int x = 0, w = source.getWidth(); x < w; x += 4) {
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extract4x4RGBA(block, source, x, y);
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stb_compress_dxt_block(dst, block, dxt5, 8);
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dst += dxt5 ? 16 : 8;
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}
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}
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return {
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.format = config.format,
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.size = size,
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.data = decltype(CompressedTexture::data)(buffer)
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};
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}
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S3tcConfig s3tcParseOptionString(const std::string& options) {
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if (options == "rgb_dxt1") {
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return {CompressedFormat::RGB_S3TC_DXT1, false};
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}
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if (options == "rgba_dxt5") {
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return {CompressedFormat::RGBA_S3TC_DXT5, false};
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}
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return {};
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}
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static LinearImage extendToFourChannels(LinearImage original) {
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LinearImage source = original;
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const uint32_t width = source.getWidth();
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const uint32_t height = source.getHeight();
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auto createEmptyImage = [width, height](float value) {
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auto result = LinearImage(width, height, 1);
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float* pixels = result.getPixelRef(0, 0);
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std::fill(pixels, pixels + width * height, value);
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return result;
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};
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switch (source.getChannels()) {
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case 4: break;
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case 1: {
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auto l = image::extractChannel(source, 0);
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auto a = createEmptyImage(1.0f);
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source = image::combineChannels({l, l, l, a});
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}
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case 2: {
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auto l = image::extractChannel(source, 0);
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auto a = image::extractChannel(source, 1);
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source = image::combineChannels({l, l, l, a});
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}
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case 3: {
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auto r = image::extractChannel(source, 0);
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auto g = image::extractChannel(source, 1);
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auto b = image::extractChannel(source, 2);
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auto a = createEmptyImage(1.0f);
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source = image::combineChannels({r, g, b, a});
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}
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default: {
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auto r = image::extractChannel(source, 0);
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auto g = image::extractChannel(source, 1);
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auto b = image::extractChannel(source, 2);
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auto a = image::extractChannel(source, 3);
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source = image::combineChannels({r, g, b, a});
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}
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}
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return source;
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}
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} // namespace image
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