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#include <mbgl/geometry/line_atlas.hpp>
#include <mbgl/gfx/upload_pass.hpp>
#include <mbgl/util/logging.hpp>
#include <mbgl/util/platform.hpp>
#include <mbgl/util/hash.hpp>
#include <cmath>
namespace mbgl {
LineAtlas::LineAtlas(const Size size)
: image(size),
dirty(true) {
}
LineAtlas::~LineAtlas() = default;
LinePatternPos LineAtlas::getDashPosition(const std::vector<float>& dasharray,
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);
}
// Note: We're not handling hash collisions here.
const auto it = positions.find(key);
if (it == positions.end()) {
auto inserted = positions.emplace(key, addDash(dasharray, patternCap));
assert(inserted.second);
return inserted.first->second;
} else {
return it->second;
}
}
LinePatternPos LineAtlas::addDash(const std::vector<float>& dasharray, LinePatternCap patternCap) {
const uint8_t n = patternCap == LinePatternCap::Round ? 7 : 0;
const uint8_t dashheight = 2 * n + 1;
const uint8_t offset = 128;
if (dasharray.size() < 2) {
return LinePatternPos();
}
if (nextRow + dashheight > image.size.height) {
Log::Warning(Event::OpenGL, "line atlas bitmap overflow");
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 = nextRow + 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 + nextRow + n) / image.size.height;
position.height = (2.0 * n) / image.size.height;
position.width = length;
nextRow += dashheight;
dirty = true;
return position;
}
Size LineAtlas::getSize() const {
return image.size;
}
void LineAtlas::upload(gfx::UploadPass& uploadPass) {
if (!texture) {
texture = uploadPass.createTexture(image);
} else if (dirty) {
uploadPass.updateTexture(*texture, image);
}
dirty = false;
}
gfx::TextureBinding LineAtlas::textureBinding() {
assert(texture);
// All _changes_ to the texture should've been made and uploaded already.
assert(!dirty);
return { texture->getResource(), gfx::TextureFilterType::Linear, gfx::TextureMipMapType::No,
gfx::TextureWrapType::Repeat, gfx::TextureWrapType::Clamp };
}
} // namespace mbgl
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