bool Label::updateScreenTransform(const glm::mat4& _mvp, const glm::vec2& _screenSize, bool _testVisibility) {
glm::vec2 screenPosition;
float rot = 0;
glm::vec2 ap1, ap2;
switch (m_type) {
case Type::debug:
case Type::point:
{
glm::vec4 v1 = worldToClipSpace(_mvp, glm::vec4(m_transform.modelPosition1, 0.0, 1.0));
if (_testVisibility && (v1.w <= 0)) {
return false;
}
screenPosition = clipToScreenSpace(v1, _screenSize);
ap1 = ap2 = screenPosition;
break;
}
case Type::line:
{
// project label position from mercator world space to clip coordinates
glm::vec4 v1 = worldToClipSpace(_mvp, glm::vec4(m_transform.modelPosition1, 0.0, 1.0));
glm::vec4 v2 = worldToClipSpace(_mvp, glm::vec4(m_transform.modelPosition2, 0.0, 1.0));
// check whether the label is behind the camera using the perspective division factor
if (_testVisibility && (v1.w <= 0 || v2.w <= 0)) {
return false;
}
// project to screen space
glm::vec2 p1 = clipToScreenSpace(v1, _screenSize);
glm::vec2 p2 = clipToScreenSpace(v2, _screenSize);
rot = angleBetweenPoints(p1, p2) + M_PI_2;
if (rot > M_PI_2 || rot < -M_PI_2) { // un-readable labels
rot += M_PI;
} else {
std::swap(p1, p2);
}
float length = glm::length(p2 - p1);
float exceedHeuristic = 30; // default heuristic : 30%
if (_testVisibility && (m_dim.x > length)) {
float exceed = (1 - (length / m_dim.x)) * 100;
if (exceed > exceedHeuristic) {
return false;
}
}
ap1 = p1;
ap2 = p2;
break;
}
}
align(screenPosition, ap1, ap2);
// update screen position
glm::vec2 offset = m_options.offset;
if (m_transform.state.rotation != 0.f) {
offset = glm::rotate(offset, m_transform.state.rotation);
}
glm::vec2 newScreenPos = screenPosition + offset;
if (newScreenPos != m_transform.state.screenPos) {
m_transform.state.screenPos = newScreenPos;
m_dirty = true;
}
// update screen rotation
if (m_transform.state.rotation != rot) {
m_transform.state.rotation = rot;
m_dirty = true;
}
return true;
}
glm::vec2 worldToScreenSpace(const glm::mat4& _mvp, const glm::vec4& _worldPosition, const glm::vec2& _screenSize) {
return clipToScreenSpace(worldToClipSpace(_mvp, _worldPosition), _screenSize);
}
