多通道有向距离场图集生成器

#include <msdf-atlas-gen/msdf-atlas-gen.h>

using namespace msdf_atlas;

bool generateAtlas(const char *fontFilename) {
    bool success = false;
    // Initialize instance of FreeType library
    if (msdfgen::FreetypeHandle *ft = msdfgen::initializeFreetype()) {
        // Load font file
        if (msdfgen::FontHandle *font = msdfgen::loadFont(ft, fontFilename)) {
            // Storage for glyph geometry and their coordinates in the atlas
            std::vector<GlyphGeometry> glyphs;
            // FontGeometry is a helper class that loads a set of glyphs from a single font.
            // It can also be used to get additional font metrics, kerning information, etc.
            FontGeometry fontGeometry(&glyphs);
            // Load a set of character glyphs:
            // The second argument can be ignored unless you mix different font sizes in one atlas.
            // In the last argument, you can specify a charset other than ASCII.
            // To load specific glyph indices, use loadGlyphs instead.
            fontGeometry.loadCharset(font, 1.0, Charset::ASCII);
            // Apply MSDF edge coloring. See edge-coloring.h for other coloring strategies.
            const double maxCornerAngle = 3.0;
            for (GlyphGeometry &glyph : glyphs)
                glyph.edgeColoring(&msdfgen::edgeColoringInkTrap, maxCornerAngle, 0);
            // TightAtlasPacker class computes the layout of the atlas.
            TightAtlasPacker packer;
            // Set atlas parameters:
            // setDimensions or setDimensionsConstraint to find the best value
            packer.setDimensionsConstraint(TightAtlasPacker::DimensionsConstraint::SQUARE);
            // setScale for a fixed size or setMinimumScale to use the largest that fits
            packer.setMinimumScale(24.0);
            // setPixelRange or setUnitRange
            packer.setPixelRange(2.0);
            packer.setMiterLimit(1.0);
            // Compute atlas layout - pack glyphs
            packer.pack(glyphs.data(), glyphs.size());
            // Get final atlas dimensions
            int width = 0, height = 0;
            packer.getDimensions(width, height);
            // The ImmediateAtlasGenerator class facilitates the generation of the atlas bitmap.
            ImmediateAtlasGenerator<
                float, // pixel type of buffer for individual glyphs depends on generator function
                3, // number of atlas color channels
                &msdfGenerator, // function to generate bitmaps for individual glyphs
                BitmapAtlasStorage<byte, 3> // class that stores the atlas bitmap
                // For example, a custom atlas storage class that stores it in VRAM can be used.
            > generator(width, height);
            // GeneratorAttributes can be modified to change the generator's default settings.
            GeneratorAttributes attributes;
            generator.setAttributes(attributes);
            generator.setThreadCount(4);
            // Generate atlas bitmap
            generator.generate(glyphs.data(), glyphs.size());
            // The atlas bitmap can now be retrieved via atlasStorage as a BitmapConstRef.
            // The glyphs array (or fontGeometry) contains positioning data for typesetting text.
            success = myProject::submitAtlasBitmapAndLayout(generator.atlasStorage(), glyphs);
            // Cleanup
            msdfgen::destroyFont(font);
        }
        msdfgen::deinitializeFreetype(ft);
    }
    return success;
}

#include <msdf-atlas-gen/msdf-atlas-gen.h>

using namespace msdf_atlas;

using MyDynamicAtlas = DynamicAtlas<ImmediateAtlasGenerator<float, 3, &msdfGenerator, BitmapAtlasStorage<byte, 3>>>;

const double pixelRange = 2.0;
const double glyphScale = 32.0;
const double miterLimit = 1.0;
const double maxCornerAngle = 3.0;

MyDynamicAtlas atlas;

void addGlyphsToAtlas(GlyphGeometry *glyphs, int count) {
    for (int i = 0; i < count; ++i) {
        // Apply MSDF edge coloring. See edge-coloring.h for other coloring strategies.
        glyphs[i].edgeColoring(&msdfgen::edgeColoringInkTrap, maxCornerAngle, 0);
        // Finalize glyph box size based on the parameters
        glyphs[i].wrapBox(glyphScale, pixelRange/glyphScale, miterLimit);
    }
    // Add glyphs to atlas - invokes the underlying atlas generator
    // Adding multiple glyphs at once may improve packing efficiency.
    MyDynamicAtlas::ChangeFlags change = atlas.add(glyphs, count);
    if (change&MyDynamicAtlas::RESIZED) {
        // Atlas has been enlarged - can be handled here or directly in custom generator class
    }
    // Glyph positioning data is now stored in glyphs.
}