Typography improvements
This commit is contained in:
@@ -13,9 +13,9 @@
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namespace
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{
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constexpr int kTextSdfSpread = 20;
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constexpr unsigned kTextSdfBlurPasses = 1;
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constexpr float kTextFontPixelSize = 144.0f;
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constexpr float kTextLayoutPadding = 48.0f;
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constexpr float kSdfInfinity = 1.0e20f;
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class GdiplusSession
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{
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@@ -54,128 +54,115 @@ std::wstring Utf8ToWide(const std::string& text)
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return wide;
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}
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std::vector<unsigned char> BuildLocalSdf(const std::vector<unsigned char>& alpha, unsigned width, unsigned height)
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void DistanceTransform1D(const std::vector<float>& input, std::vector<float>& output, unsigned count)
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{
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std::vector<unsigned char> sdf(static_cast<std::size_t>(width) * height * 4, 0);
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std::vector<unsigned> locations(count, 0);
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std::vector<float> boundaries(static_cast<std::size_t>(count) + 1, 0.0f);
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unsigned segment = 0;
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locations[0] = 0;
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boundaries[0] = -kSdfInfinity;
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boundaries[1] = kSdfInfinity;
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for (unsigned q = 1; q < count; ++q)
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{
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float intersection = 0.0f;
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for (;;)
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{
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const unsigned location = locations[segment];
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intersection =
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((input[q] + static_cast<float>(q * q)) - (input[location] + static_cast<float>(location * location))) /
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(2.0f * static_cast<float>(q) - 2.0f * static_cast<float>(location));
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if (intersection > boundaries[segment] || segment == 0)
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break;
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--segment;
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}
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++segment;
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locations[segment] = q;
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boundaries[segment] = intersection;
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boundaries[segment + 1] = kSdfInfinity;
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}
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segment = 0;
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for (unsigned q = 0; q < count; ++q)
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{
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while (boundaries[segment + 1] < static_cast<float>(q))
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++segment;
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const unsigned location = locations[segment];
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const float delta = static_cast<float>(q) - static_cast<float>(location);
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output[q] = delta * delta + input[location];
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}
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}
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std::vector<float> DistanceTransform2D(const std::vector<unsigned char>& targetMask, unsigned width, unsigned height)
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{
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std::vector<float> rowInput(width, 0.0f);
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std::vector<float> rowOutput(width, 0.0f);
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std::vector<float> columnInput(height, 0.0f);
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std::vector<float> columnOutput(height, 0.0f);
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std::vector<float> rowDistance(static_cast<std::size_t>(width) * height, 0.0f);
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std::vector<float> distance(static_cast<std::size_t>(width) * height, 0.0f);
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for (unsigned y = 0; y < height; ++y)
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{
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for (unsigned x = 0; x < width; ++x)
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{
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const bool inside = alpha[static_cast<std::size_t>(y) * width + x] > 127;
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int bestDistanceSq = kTextSdfSpread * kTextSdfSpread;
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for (int oy = -kTextSdfSpread; oy <= kTextSdfSpread; ++oy)
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{
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const int sy = static_cast<int>(y) + oy;
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if (sy < 0 || sy >= static_cast<int>(height))
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continue;
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for (int ox = -kTextSdfSpread; ox <= kTextSdfSpread; ++ox)
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{
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const int sx = static_cast<int>(x) + ox;
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if (sx < 0 || sx >= static_cast<int>(width))
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continue;
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const bool sampleInside = alpha[static_cast<std::size_t>(sy) * width + sx] > 127;
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if (sampleInside == inside)
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continue;
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const int distanceSq = ox * ox + oy * oy;
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if (distanceSq < bestDistanceSq)
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bestDistanceSq = distanceSq;
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}
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}
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rowInput[x] = targetMask[static_cast<std::size_t>(y) * width + x] ? 0.0f : kSdfInfinity;
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DistanceTransform1D(rowInput, rowOutput, width);
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for (unsigned x = 0; x < width; ++x)
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rowDistance[static_cast<std::size_t>(y) * width + x] = rowOutput[x];
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}
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const float distance = std::sqrt(static_cast<float>(bestDistanceSq));
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const float signedDistance = (inside ? 1.0f : -1.0f) * distance;
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float normalized = 0.5f + signedDistance / static_cast<float>(kTextSdfSpread * 2);
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const unsigned char sourceAlpha = alpha[static_cast<std::size_t>(y) * width + x];
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if (sourceAlpha > 0 && sourceAlpha < 255)
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normalized = static_cast<float>(sourceAlpha) / 255.0f;
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if (normalized < 0.0f)
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normalized = 0.0f;
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if (normalized > 1.0f)
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normalized = 1.0f;
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for (unsigned x = 0; x < width; ++x)
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{
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for (unsigned y = 0; y < height; ++y)
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columnInput[y] = rowDistance[static_cast<std::size_t>(y) * width + x];
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DistanceTransform1D(columnInput, columnOutput, height);
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for (unsigned y = 0; y < height; ++y)
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distance[static_cast<std::size_t>(y) * width + x] = columnOutput[y];
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}
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return distance;
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}
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std::vector<unsigned char> BuildTextSdfTexture(const std::vector<unsigned char>& alpha, unsigned width, unsigned height)
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{
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std::vector<unsigned char> insideMask(static_cast<std::size_t>(width) * height, 0);
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std::vector<unsigned char> outsideMask(static_cast<std::size_t>(width) * height, 0);
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for (std::size_t index = 0; index < alpha.size(); ++index)
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{
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const bool inside = alpha[index] > 127;
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insideMask[index] = inside ? 1 : 0;
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outsideMask[index] = inside ? 0 : 1;
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}
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const std::vector<float> distanceToInside = DistanceTransform2D(insideMask, width, height);
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const std::vector<float> distanceToOutside = DistanceTransform2D(outsideMask, width, height);
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std::vector<unsigned char> sdf(static_cast<std::size_t>(width) * height * 4, 0);
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for (unsigned y = 0; y < height; ++y)
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{
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const unsigned flippedY = height - 1 - y;
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for (unsigned x = 0; x < width; ++x)
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{
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const std::size_t source = static_cast<std::size_t>(y) * width + x;
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const float signedDistance = std::sqrt(distanceToOutside[source]) - std::sqrt(distanceToInside[source]);
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const float normalized = std::clamp(
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0.5f + signedDistance / static_cast<float>(kTextSdfSpread * 2),
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0.0f,
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1.0f);
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const unsigned char value = static_cast<unsigned char>(normalized * 255.0f + 0.5f);
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const std::size_t out = (static_cast<std::size_t>(y) * width + x) * 4;
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const std::size_t out = (static_cast<std::size_t>(flippedY) * width + x) * 4;
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sdf[out + 0] = value;
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sdf[out + 1] = value;
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sdf[out + 2] = value;
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sdf[out + 3] = value;
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}
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}
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return sdf;
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}
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std::vector<unsigned char> BuildTextCoverageTexture(const std::vector<unsigned char>& alpha, unsigned width, unsigned height)
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{
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std::vector<unsigned char> coverage(static_cast<std::size_t>(width) * height * 4, 0);
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for (unsigned y = 0; y < height; ++y)
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{
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for (unsigned x = 0; x < width; ++x)
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{
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const unsigned char value = alpha[static_cast<std::size_t>(y) * width + x];
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const std::size_t out = (static_cast<std::size_t>(y) * width + x) * 4;
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coverage[out + 0] = value;
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coverage[out + 1] = value;
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coverage[out + 2] = value;
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coverage[out + 3] = value;
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}
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}
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return coverage;
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}
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std::vector<unsigned char> FlipTextTextureForShaderUv(const std::vector<unsigned char>& pixels, unsigned width, unsigned height)
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{
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std::vector<unsigned char> flipped(pixels.size(), 0);
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const std::size_t stride = static_cast<std::size_t>(width) * 4;
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for (unsigned y = 0; y < height; ++y)
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{
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const std::size_t srcOffset = static_cast<std::size_t>(y) * stride;
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const std::size_t dstOffset = static_cast<std::size_t>(height - 1 - y) * stride;
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std::memcpy(flipped.data() + dstOffset, pixels.data() + srcOffset, stride);
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}
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return flipped;
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}
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std::vector<unsigned char> BlurTextSdf(const std::vector<unsigned char>& pixels, unsigned width, unsigned height, unsigned passes)
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{
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std::vector<unsigned char> current = pixels;
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std::vector<unsigned char> next(pixels.size(), 0);
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for (unsigned pass = 0; pass < passes; ++pass)
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{
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for (unsigned y = 0; y < height; ++y)
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{
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for (unsigned x = 0; x < width; ++x)
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{
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unsigned weightedTotal = 0;
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unsigned weightSum = 0;
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for (int oy = -1; oy <= 1; ++oy)
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{
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const int sy = static_cast<int>(y) + oy;
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if (sy < 0 || sy >= static_cast<int>(height))
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continue;
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for (int ox = -1; ox <= 1; ++ox)
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{
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const int sx = static_cast<int>(x) + ox;
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if (sx < 0 || sx >= static_cast<int>(width))
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continue;
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const unsigned weight = (ox == 0 && oy == 0) ? 4u : ((ox == 0 || oy == 0) ? 2u : 1u);
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const std::size_t sample = (static_cast<std::size_t>(sy) * width + sx) * 4;
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weightedTotal += static_cast<unsigned>(current[sample]) * weight;
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weightSum += weight;
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}
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}
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const unsigned char value = static_cast<unsigned char>((weightedTotal + weightSum / 2) / weightSum);
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const std::size_t out = (static_cast<std::size_t>(y) * width + x) * 4;
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next[out + 0] = value;
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next[out + 1] = value;
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next[out + 2] = value;
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next[out + 3] = value;
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}
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}
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current.swap(next);
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}
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return current;
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}
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void WriteTextMaskDebugDump(const std::string& text, const std::vector<unsigned char>& alpha, const std::vector<unsigned char>& sdf, unsigned width, unsigned height)
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{
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try
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@@ -308,9 +295,7 @@ bool RasterizeTextSdf(const std::string& text, const std::filesystem::path& font
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alpha[static_cast<std::size_t>(y) * kTextTextureWidth + x] = static_cast<unsigned char>(luminance);
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}
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}
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sdf = BuildTextCoverageTexture(alpha, kTextTextureWidth, kTextTextureHeight);
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sdf = BlurTextSdf(sdf, kTextTextureWidth, kTextTextureHeight, kTextSdfBlurPasses);
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sdf = FlipTextTextureForShaderUv(sdf, kTextTextureWidth, kTextTextureHeight);
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sdf = BuildTextSdfTexture(alpha, kTextTextureWidth, kTextTextureHeight);
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WriteTextMaskDebugDump(text, alpha, sdf, kTextTextureWidth, kTextTextureHeight);
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return true;
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}
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