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#include <mbgl/geometry/line_atlas.hpp>
#include <mbgl/gfx/upload_pass.hpp>
#include <mbgl/math/minmax.hpp>
#include <mbgl/util/hash.hpp>
#include <mbgl/util/logging.hpp>
#include <mbgl/util/platform.hpp>
#include <cmath>
namespace mbgl {
namespace {
size_t getDashPatternHash(const std::vector<float>& dasharray, const LinePatternCap patternCap) {
size_t key =
patternCap == LinePatternCap::Round ? std::numeric_limits<size_t>::min() : std::numeric_limits<size_t>::max();
for (const float part : dasharray) {
util::hash_combine<float>(key, part);
}
return key;
}
LinePatternPos addDashPattern(AlphaImage& image,
const int32_t yOffset,
const std::vector<float>& dasharray,
const LinePatternCap patternCap) {
const uint8_t n = patternCap == LinePatternCap::Round ? 7 : 0;
constexpr const uint8_t offset = 128;
if (dasharray.size() < 2) {
Log::Warning(Event::ParseStyle, "line dasharray requires at least two elements");
return LinePatternPos();
}
float length = 0;
for (const float part : dasharray) {
length += part;
}
float stretch = image.size.width / length;
float halfWidth = stretch * 0.5;
// If dasharray has an odd length, both the first and last parts
// are dashes and should be joined seamlessly.
bool oddLength = dasharray.size() % 2 == 1;
for (int y = -n; y <= n; y++) {
int row = yOffset + n + y;
int index = image.size.width * row;
float left = 0;
float right = dasharray[0];
unsigned int partIndex = 1;
if (oddLength) {
left -= dasharray.back();
}
for (uint32_t x = 0; x < image.size.width; x++) {
while (right < x / stretch) {
left = right;
if (partIndex >= dasharray.size()) {
return LinePatternPos();
}
right = right + dasharray[partIndex];
if (oddLength && partIndex == dasharray.size() - 1) {
right += dasharray.front();
}
partIndex++;
}
float distLeft = fabs(x - left * stretch);
float distRight = fabs(x - right * stretch);
float dist = fmin(distLeft, distRight);
bool inside = (partIndex % 2) == 1;
int signedDistance;
if (patternCap == LinePatternCap::Round) {
float distMiddle = n ? (float)y / n * (halfWidth + 1) : 0;
if (inside) {
float distEdge = halfWidth - fabs(distMiddle);
signedDistance = sqrt(dist * dist + distEdge * distEdge);
} else {
signedDistance = halfWidth - sqrt(dist * dist + distMiddle * distMiddle);
}
} else {
signedDistance = int((inside ? 1 : -1) * dist);
}
image.data[index + x] = fmax(0, fmin(255, signedDistance + offset));
}
}
LinePatternPos position;
position.y = (0.5 + yOffset + n) / image.size.height;
position.height = (2.0 * n + 1) / image.size.height;
position.width = length;
return position;
}
} // namespace
DashPatternTexture::DashPatternTexture(const std::vector<float>& from_,
const std::vector<float>& to_,
const LinePatternCap cap) {
const bool patternsIdentical = from_ == to_;
const int32_t patternHeight = cap == LinePatternCap::Round ? 15 : 1;
AlphaImage image({256, static_cast<uint32_t>((patternsIdentical ? 1 : 2) * patternHeight)});
from = addDashPattern(image, 0, from_, cap);
to = patternsIdentical ? from : addDashPattern(image, patternHeight, to_, cap);
texture = std::move(image);
}
void DashPatternTexture::upload(gfx::UploadPass& uploadPass) {
if (texture.is<AlphaImage>()) {
texture = uploadPass.createTexture(texture.get<AlphaImage>());
}
}
gfx::TextureBinding DashPatternTexture::textureBinding() const {
// The texture needs to have been uploaded already.
assert(texture.is<gfx::Texture>());
return {texture.get<gfx::Texture>().getResource(),
gfx::TextureFilterType::Linear,
gfx::TextureMipMapType::No,
gfx::TextureWrapType::Repeat,
gfx::TextureWrapType::Clamp};
}
Size DashPatternTexture::getSize() const {
return texture.match([](const auto& obj) { return obj.size; });
}
LineAtlas::LineAtlas() = default;
LineAtlas::~LineAtlas() = default;
DashPatternTexture& LineAtlas::getDashPatternTexture(const std::vector<float>& from,
const std::vector<float>& to,
const LinePatternCap cap) {
const size_t hash = util::hash(getDashPatternHash(from, cap), getDashPatternHash(to, cap));
// Note: We're not handling hash collisions here.
const auto it = textures.find(hash);
if (it == textures.end()) {
auto inserted = textures.emplace(
std::piecewise_construct, std::forward_as_tuple(hash), std::forward_as_tuple(from, to, cap));
assert(inserted.second);
needsUpload.emplace_back(hash);
return inserted.first->second;
} else {
return it->second;
}
}
void LineAtlas::upload(gfx::UploadPass& uploadPass) {
for (const size_t hash : needsUpload) {
const auto it = textures.find(hash);
if (it != textures.end()) {
it->second.upload(uploadPass);
}
}
needsUpload.clear();
}
} // namespace mbgl
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