Refactor TransformState to use internal 3d camera

CMakeLists.txt

@@ -749,6 +749,7 @@ add_library(
     ${PROJECT_SOURCE_DIR}/src/mbgl/tile/vector_tile.hpp
     ${PROJECT_SOURCE_DIR}/src/mbgl/tile/vector_tile_data.cpp
     ${PROJECT_SOURCE_DIR}/src/mbgl/tile/vector_tile_data.hpp
+    ${PROJECT_SOURCE_DIR}/src/mbgl/util/camera.cpp
     ${PROJECT_SOURCE_DIR}/src/mbgl/util/bounding_volumes.hpp
     ${PROJECT_SOURCE_DIR}/src/mbgl/util/bounding_volumes.cpp
     ${PROJECT_SOURCE_DIR}/src/mbgl/util/chrono.cpp

src/mbgl/map/transform_state.cpp

@@ -9,6 +9,15 @@
 #include <mbgl/util/tile_coordinate.hpp>
 
 namespace mbgl {
+
+namespace {
+LatLng latLngFromMercator(Point<double> mercatorCoordinate, LatLng::WrapMode wrapMode = LatLng::WrapMode::Unwrapped) {
+    return {util::RAD2DEG * (2 * std::atan(std::exp(M_PI - mercatorCoordinate.y * util::M2PI)) - M_PI_2),
+            mercatorCoordinate.x * 360.0 - 180.0,
+            wrapMode};
+}
+} // namespace
+
 TransformState::TransformState(ConstrainMode constrainMode_, ViewportMode viewportMode_)
     : bounds(LatLngBounds()), constrainMode(constrainMode_), viewportMode(viewportMode_) {}
 
@@ -101,62 +110,52 @@ void TransformState::getProjMatrix(mat4& projMatrix, uint16_t nearZ, bool aligne
     // Add a bit extra to avoid precision problems when a fragment's distance is exactly `furthestDistance`
     const double farZ = furthestDistance * 1.01;
 
-    matrix::perspective(projMatrix, getFieldOfView(), double(size.width) / size.height, nearZ, farZ);
+    // Make sure the camera state is up-to-date
+    updateCameraState();
+
+    mat4 worldToCamera = camera.getWorldToCamera(scale, viewportMode == ViewportMode::FlippedY);
+    mat4 cameraToClip =
+        camera.getCameraToClipPerspective(getFieldOfView(), double(size.width) / size.height, nearZ, farZ);
 
     // Move the center of perspective to center of specified edgeInsets.
     // Values are in range [-1, 1] where the upper and lower range values
     // position viewport center to the screen edges. This is overriden
     // if using axonometric perspective (not in public API yet, Issue #11882).
     // TODO(astojilj): Issue #11882 should take edge insets into account, too.
-    projMatrix[8] = -offset.x * 2.0 / size.width;
-    projMatrix[9] = offset.y * 2.0 / size.height;
-
-    const bool flippedY = viewportMode == ViewportMode::FlippedY;
-    matrix::scale(projMatrix, projMatrix, 1.0, flippedY ? 1 : -1, 1);
-
-    matrix::translate(projMatrix, projMatrix, 0, 0, -cameraToCenterDistance);
-
-    using NO = NorthOrientation;
-    switch (getNorthOrientation()) {
-        case NO::Rightwards:
-            matrix::rotate_y(projMatrix, projMatrix, getPitch());
-            break;
-        case NO::Downwards:
-            matrix::rotate_x(projMatrix, projMatrix, -getPitch());
-            break;
-        case NO::Leftwards:
-            matrix::rotate_y(projMatrix, projMatrix, -getPitch());
-            break;
-        default:
-            matrix::rotate_x(projMatrix, projMatrix, getPitch());
-            break;
+    if (!axonometric) {
+        cameraToClip[8] = -offset.x * 2.0 / size.width;
+        cameraToClip[9] = offset.y * 2.0 / size.height;
     }
 
-    matrix::rotate_z(projMatrix, projMatrix, getBearing() + getNorthOrientationAngle());
+    // Apply north orientation angle
+    if (getNorthOrientation() != NorthOrientation::Upwards) {
+        matrix::rotate_z(cameraToClip, cameraToClip, -getNorthOrientationAngle());
+    }
 
-    const double dx = pixel_x() - size.width / 2.0f;
-    const double dy = pixel_y() - size.height / 2.0f;
-    matrix::translate(projMatrix, projMatrix, dx, dy, 0);
+    matrix::multiply(projMatrix, cameraToClip, worldToCamera);
 
     if (axonometric) {
         // mat[11] controls perspective
-        projMatrix[11] = 0;
+        projMatrix[11] = 0.0;
 
         // mat[8], mat[9] control x-skew, y-skew
-        projMatrix[8] = xSkew;
-        projMatrix[9] = ySkew;
+        double pixelsPerMeter = 1.0 / Projection::getMetersPerPixelAtLatitude(getLatLng().latitude(), getZoom());
+        projMatrix[8] = xSkew * pixelsPerMeter;
+        projMatrix[9] = ySkew * pixelsPerMeter;
     }
 
-    matrix::scale(projMatrix, projMatrix, 1, 1,
-                  1.0 / Projection::getMetersPerPixelAtLatitude(getLatLng(LatLng::Unwrapped).latitude(), getZoom()));
-
     // Make a second projection matrix that is aligned to a pixel grid for rendering raster tiles.
     // We're rounding the (floating point) x/y values to achieve to avoid rendering raster images to fractional
     // coordinates. Additionally, we adjust by half a pixel in either direction in case that viewport dimension
     // is an odd integer to preserve rendering to the pixel grid. We're rotating this shift based on the angle
     // of the transformation so that 0°, 90°, 180°, and 270° rasters are crisp, and adjust the shift so that
     // it is always <= 0.5 pixels.
+
     if (aligned) {
+        const double worldSize = Projection::worldSize(scale);
+        const double dx = x - 0.5 * worldSize;
+        const double dy = y - 0.5 * worldSize;
+
         const float xShift = float(size.width % 2) / 2;
         const float yShift = float(size.height % 2) / 2;
         const double bearingCos = std::cos(bearing);
@@ -168,6 +167,65 @@ void TransformState::getProjMatrix(mat4& projMatrix, uint16_t nearZ, bool aligne
     }
 }
 
+void TransformState::updateCameraState() const {
+    if (!valid()) {
+        return;
+    }
+
+    const double worldSize = Projection::worldSize(scale);
+    const double cameraToCenterDistance = getCameraToCenterDistance();
+
+    // x & y tracks the center of the map in pixels. However as rendering is done in pixel coordinates the rendering
+    // origo is actually in the middle of the map (0.5 * worldSize). x&y positions have to be negated because it defines
+    // position of the map, not the camera. Moving map 10 units left has the same effect as moving camera 10 units to the
+    // right.
+    const double dx = 0.5 * worldSize - x;
+    const double dy = 0.5 * worldSize - y;
+
+    // Set camera orientation and move it to a proper distance from the map
+    camera.setOrientation(getPitch(), getBearing());
+
+    const vec3 forward = camera.forward();
+    const vec3 orbitPosition = {{-forward[0] * cameraToCenterDistance,
+                                 -forward[1] * cameraToCenterDistance,
+                                 -forward[2] * cameraToCenterDistance}};
+    vec3 cameraPosition = {{dx + orbitPosition[0], dy + orbitPosition[1], orbitPosition[2]}};
+
+    cameraPosition[0] /= worldSize;
+    cameraPosition[1] /= worldSize;
+    cameraPosition[2] /= worldSize;
+
+    camera.setPosition(cameraPosition);
+}
+
+void TransformState::updateStateFromCamera() {
+    const vec3 position = camera.getPosition();
+    const vec3 forward = camera.forward();
+
+    const double dx = forward[0];
+    const double dy = forward[1];
+    const double dz = forward[2];
+    assert(position[2] > 0.0 && dz < 0.0);
+
+    // Compute bearing and pitch
+    double newBearing;
+    double newPitch;
+    camera.getOrientation(newPitch, newBearing);
+    newPitch = util::clamp(newPitch, minPitch, maxPitch);
+
+    // Compute zoom level from the camera altitude
+    const double centerDistance = getCameraToCenterDistance();
+    const double zoom = util::log2(centerDistance / (position[2] / std::cos(newPitch) * util::tileSize));
+    const double newScale = util::clamp(std::pow(2.0, zoom), min_scale, max_scale);
+
+    // Compute center point of the map
+    const double travel = -position[2] / dz;
+    const Point<double> mercatorPoint = {position[0] + dx * travel, position[1] + dy * travel};
+
+    setLatLngZoom(latLngFromMercator(mercatorPoint), scaleZoom(newScale));
+    setBearing(newBearing);
+    setPitch(newPitch);
+}
 void TransformState::updateMatricesIfNeeded() const {
     if (!needsMatricesUpdate() || size.isEmpty()) return;
 

src/mbgl/map/transform_state.hpp

@@ -1,13 +1,14 @@
 #pragma once
 
-#include <mbgl/map/mode.hpp>
 #include <mbgl/map/camera.hpp>
+#include <mbgl/map/mode.hpp>
+#include <mbgl/util/camera.hpp>
+#include <mbgl/util/constants.hpp>
 #include <mbgl/util/geo.hpp>
 #include <mbgl/util/geometry.hpp>
-#include <mbgl/util/constants.hpp>
+#include <mbgl/util/mat4.hpp>
 #include <mbgl/util/optional.hpp>
 #include <mbgl/util/projection.hpp>
-#include <mbgl/util/mat4.hpp>
 #include <mbgl/util/size.hpp>
 
 #include <cstdint>
@@ -248,6 +249,9 @@ private:
     void updateMatricesIfNeeded() const;
     bool needsMatricesUpdate() const { return requestMatricesUpdate; }
 
+    void updateCameraState() const;
+    void updateStateFromCamera();
+
     const mat4& getCoordMatrix() const;
     const mat4& getInvertedMatrix() const;
 
@@ -276,6 +280,7 @@ private:
     bool axonometric = false;
 
     EdgeInsets edgeInsets;
+    mutable util::Camera camera;
 
     // cache values for spherical mercator math
     double Bc = Projection::worldSize(scale) / util::DEGREES_MAX;

src/mbgl/util/camera.cpp

@@ -0,0 +1,215 @@
+#include "camera.hpp"
+#include <cassert>
+#include <cmath>
+#include <mbgl/map/camera.hpp>
+#include <mbgl/math/log2.hpp>
+#include <mbgl/util/constants.hpp>
+#include <mbgl/util/geo.hpp>
+#include <mbgl/util/projection.hpp>
+
+namespace mbgl {
+
+namespace {
+double vec2Len(const vec2& v) {
+    return std::sqrt(v[0] * v[0] + v[1] * v[1]);
+};
+
+double vec2Dot(const vec2& a, const vec2& b) {
+    return a[0] * b[0] + a[1] * b[1];
+};
+
+vec2 vec2Scale(const vec2& v, double s) {
+    return vec2{{v[0] * s, v[1] * s}};
+};
+} // namespace
+
+namespace util {
+
+static double mercatorXfromLng(double lng) {
+    return (180.0 + lng) / 360.0;
+}
+
+static double mercatorYfromLat(double lat) {
+    return (180.0 - (180.0 / M_PI * std::log(std::tan(M_PI_4 + lat * M_PI / 360.0)))) / 360.0;
+}
+
+static double latFromMercatorY(double y) {
+    return util::RAD2DEG * (2.0 * std::atan(std::exp(M_PI - y * util::M2PI)) - M_PI_2);
+}
+
+static double lngFromMercatorX(double x) {
+    return x * 360.0 - 180.0;
+}
+
+static double* getColumn(mat4& matrix, int col) {
+    assert(col >= 0 && col < 4);
+    return &matrix[col * 4];
+}
+
+static const double* getColumn(const mat4& matrix, int col) {
+    assert(col >= 0 && col < 4);
+    return &matrix[col * 4];
+}
+
+static vec3 toMercator(const LatLng& location, double altitudeMeters) {
+    const double pixelsPerMeter = 1.0 / Projection::getMetersPerPixelAtLatitude(location.latitude(), 0.0);
+    const double worldSize = Projection::worldSize(std::pow(2.0, 0.0));
+
+    return {{mercatorXfromLng(location.longitude()),
+             mercatorYfromLat(location.latitude()),
+             altitudeMeters * pixelsPerMeter / worldSize}};
+}
+
+static Quaternion orientationFromPitchBearing(double pitch, double bearing) {
+    // Both angles have to be negated to achieve CW rotation around the axis of rotation
+    Quaternion rotBearing = Quaternion::fromAxisAngle({{0.0, 0.0, 1.0}}, -bearing);
+    Quaternion rotPitch = Quaternion::fromAxisAngle({{1.0, 0.0, 0.0}}, -pitch);
+
+    return rotBearing.multiply(rotPitch);
+}
+
+static void updateTransform(mat4& transform, const Quaternion& orientation) {
+    // Construct rotation matrix from orientation
+    mat4 m = orientation.toRotationMatrix();
+
+    // Apply translation to the matrix
+    double* col = getColumn(m, 3);
+
+    col[0] = getColumn(transform, 3)[0];
+    col[1] = getColumn(transform, 3)[1];
+    col[2] = getColumn(transform, 3)[2];
+
+    transform = m;
+}
+
+static void updateTransform(mat4& transform, const vec3& position) {
+    getColumn(transform, 3)[0] = position[0];
+    getColumn(transform, 3)[1] = position[1];
+    getColumn(transform, 3)[2] = position[2];
+}
+
+Camera::Camera() : orientation(Quaternion::identity) {
+    matrix::identity(transform);
+}
+
+vec3 Camera::getPosition() const {
+    const double* p = getColumn(transform, 3);
+    return {{p[0], p[1], p[2]}};
+}
+
+mat4 Camera::getCameraToWorld(double scale, bool flippedY) const {
+    mat4 cameraToWorld;
+    matrix::invert(cameraToWorld, getWorldToCamera(scale, flippedY));
+    return cameraToWorld;
+}
+
+mat4 Camera::getWorldToCamera(double scale, bool flippedY) const {
+    // transformation chain from world space to camera space:
+    // 1. Height value (z) of renderables is in meters. Scale z coordinate by pixelsPerMeter
+    // 2. Transform from pixel coordinates to camera space with cameraMatrix^-1
+    // 3. flip Y if required
+
+    // worldToCamera: flip * cam^-1 * zScale
+    // cameraToWorld: (flip * cam^-1 * zScale)^-1 => (zScale^-1 * cam * flip^-1)
+    const double worldSize = Projection::worldSize(scale);
+    const double latitude = latFromMercatorY(getColumn(transform, 3)[1]);
+    const double pixelsPerMeter = worldSize / (std::cos(latitude * util::DEG2RAD) * util::M2PI * util::EARTH_RADIUS_M);
+
+    // Compute inverse of the camera matrix
+    mat4 result = orientation.conjugate().toRotationMatrix();
+
+    matrix::translate(
+        result, result, -transform[12] * worldSize, -transform[13] * worldSize, -transform[14] * worldSize);
+
+    if (!flippedY) {
+        // Pre-multiply y
+        result[1] *= -1.0;
+        result[5] *= -1.0;
+        result[9] *= -1.0;
+        result[13] *= -1.0;
+    }
+
+    // Post-multiply z
+    result[8] *= pixelsPerMeter;
+    result[9] *= pixelsPerMeter;
+    result[10] *= pixelsPerMeter;
+    result[11] *= pixelsPerMeter;
+
+    return result;
+}
+
+mat4 Camera::getCameraToClipPerspective(double fovy, double aspectRatio, double nearZ, double farZ) const {
+    mat4 projection;
+    matrix::perspective(projection, fovy, aspectRatio, nearZ, farZ);
+    return projection;
+}
+
+vec3 Camera::forward() const {
+    const double* column = getColumn(transform, 2);
+    // The forward direction is towards the map, [0, 0, -1]
+    return {{-column[0], -column[1], -column[2]}};
+}
+
+vec3 Camera::right() const {
+    const double* column = getColumn(transform, 0);
+    return {{column[0], column[1], column[2]}};
+}
+
+vec3 Camera::up() const {
+    const double* column = getColumn(transform, 1);
+    // Up direction has to be flipped due to y-axis pointing towards south
+    return {{-column[0], -column[1], -column[2]}};
+}
+
+void Camera::getOrientation(double& pitch, double& bearing) const {
+    const vec3 f = forward();
+    const vec3 r = right();
+
+    bearing = std::atan2(-r[1], r[0]);
+    pitch = std::atan2(std::sqrt(f[0] * f[0] + f[1] * f[1]), -f[2]);
+}
+
+void Camera::setOrientation(double pitch, double bearing) {
+    orientation = orientationFromPitchBearing(pitch, bearing);
+    updateTransform(transform, orientation);
+}
+
+void Camera::setOrientation(const Quaternion& orientation_) {
+    orientation = orientation_;
+    updateTransform(transform, orientation);
+}
+
+void Camera::setPosition(const vec3& position) {
+    updateTransform(transform, position);
+}
+
+optional<Quaternion> Camera::orientationFromFrame(const vec3& forward, const vec3& up) {
+    vec3 upVector = up;
+
+    vec2 xyForward = {{forward[0], forward[1]}};
+    vec2 xyUp = {{up[0], up[1]}};
+    const double epsilon = 1e-15;
+
+    // Remove roll-component of the resulting orientation by projecting
+    // the up-vector to the forward vector on xy-plane
+    if (vec2Len(xyForward) >= epsilon) {
+        const vec2 xyDir = vec2Scale(xyForward, 1.0 / vec2Len(xyForward));
+
+        xyUp = vec2Scale(xyDir, vec2Dot(xyUp, xyDir));
+        upVector[0] = xyUp[0];
+        upVector[1] = xyUp[1];
+    }
+
+    const vec3 right = vec3Cross(upVector, forward);
+
+    if (vec3Length(right) < epsilon) {
+        return nullopt;
+    }
+
+    const double bearing = std::atan2(-right[1], right[0]);
+    const double pitch = std::atan2(std::sqrt(forward[0] * forward[0] + forward[1] * forward[1]), -forward[2]);
+
+    return util::orientationFromPitchBearing(pitch, bearing);
+}
+} // namespace util
+} // namespace mbgl

src/mbgl/util/camera.hpp

@@ -0,0 +1,42 @@
+#pragma once
+
+#include <mbgl/util/optional.hpp>
+#include <mbgl/util/size.hpp>
+#include "quaternion.hpp"
+
+namespace mbgl {
+
+class LatLng;
+
+namespace util {
+
+class Camera {
+public:
+    Camera();
+
+    vec3 getPosition() const;
+    mat4 getCameraToWorld(double scale, bool flippedY) const;
+    mat4 getWorldToCamera(double scale, bool flippedY) const;
+    mat4 getCameraToClipPerspective(double fovy, double aspectRatio, double nearZ, double farZ) const;
+
+    vec3 forward() const;
+    vec3 right() const;
+    vec3 up() const;
+
+    const Quaternion& getOrientation() const { return orientation; }
+    void getOrientation(double& pitch, double& bearing) const;
+    void setOrientation(double pitch, double bearing);
+    void setOrientation(const Quaternion& orientation_);
+    void setPosition(const vec3& position);
+
+    // Computes orientation using forward and up vectors of the provided coordinate frame.
+    // Only bearing and pitch components will be used. Does not return a value if input is invalid
+    static optional<Quaternion> orientationFromFrame(const vec3& forward, const vec3& up);
+
+private:
+    Quaternion orientation;
+    mat4 transform; // Position (mercator) and orientation of the camera
+};
+
+} // namespace util
+} // namespace mbgl