Method protectEdges

MyGUIEngine/src/msdfgen/core/MSDFErrorCorrection.cpp:190–250

template <int N>
void MSDFErrorCorrection::protectEdges(const BitmapConstSection<float, N> &sdf) {
    float radius;
    stencil.reorient(sdf.yOrientation);
    // Horizontal texel pairs
    radius = float(PROTECTION_RADIUS_TOLERANCE*transformation.unprojectVector(Vector2(transformation.distanceMapping(DistanceMapping::Delta(1)), 0)).length());
    for (int y = 0; y < sdf.height; ++y) {
        const float *left = sdf(0, y);
        const float *right = sdf(1, y);
        for (int x = 0; x < sdf.width-1; ++x) {
            float lm = median(left[0], left[1], left[2]);
            float rm = median(right[0], right[1], right[2]);
            if (fabsf(lm-.5f)+fabsf(rm-.5f) < radius) {
                int mask = edgeBetweenTexels(left, right);
                protectExtremeChannels(stencil(x, y), left, lm, mask);
                protectExtremeChannels(stencil(x+1, y), right, rm, mask);
            }
            left += N, right += N;
        }
    }
    // Vertical texel pairs
    radius = float(PROTECTION_RADIUS_TOLERANCE*transformation.unprojectVector(Vector2(0, transformation.distanceMapping(DistanceMapping::Delta(1)))).length());
    for (int y = 0; y < sdf.height-1; ++y) {
        const float *bottom = sdf(0, y);
        const float *top = sdf(0, y+1);
        for (int x = 0; x < sdf.width; ++x) {
            float bm = median(bottom[0], bottom[1], bottom[2]);
            float tm = median(top[0], top[1], top[2]);
            if (fabsf(bm-.5f)+fabsf(tm-.5f) < radius) {
                int mask = edgeBetweenTexels(bottom, top);
                protectExtremeChannels(stencil(x, y), bottom, bm, mask);
                protectExtremeChannels(stencil(x, y+1), top, tm, mask);
            }
            bottom += N, top += N;
        }
    }
    // Diagonal texel pairs
    radius = float(PROTECTION_RADIUS_TOLERANCE*transformation.unprojectVector(Vector2(transformation.distanceMapping(DistanceMapping::Delta(1)))).length());
    for (int y = 0; y < sdf.height-1; ++y) {
        const float *lb = sdf(0, y);
        const float *rb = sdf(1, y);
        const float *lt = sdf(0, y+1);
        const float *rt = sdf(1, y+1);
        for (int x = 0; x < sdf.width-1; ++x) {
            float mlb = median(lb[0], lb[1], lb[2]);
            float mrb = median(rb[0], rb[1], rb[2]);
            float mlt = median(lt[0], lt[1], lt[2]);
            float mrt = median(rt[0], rt[1], rt[2]);
            if (fabsf(mlb-.5f)+fabsf(mrt-.5f) < radius) {
                int mask = edgeBetweenTexels(lb, rt);
                protectExtremeChannels(stencil(x, y), lb, mlb, mask);
                protectExtremeChannels(stencil(x+1, y+1), rt, mrt, mask);
            }
            if (fabsf(mrb-.5f)+fabsf(mlt-.5f) < radius) {
                int mask = edgeBetweenTexels(rb, lt);
                protectExtremeChannels(stencil(x+1, y), rb, mrb, mask);
                protectExtremeChannels(stencil(x, y+1), lt, mlt, mask);
            }
            lb += N, rb += N, lt += N, rt += N;