Fix for projection mismatch when aspect ratio < 1.0

This patch fixes an incorrect computation of the projection matrices and
thus a mismatch in projections between mbgl vs the other plugins when
the window A/R is less than 1.0.

Task-number: QTBUG-59417
Change-Id: Ib03eaa4c877a00c9281c335f859c854d6db632c0
Reviewed-by: Bruno de Oliveira Abinader <brunoabinader@gmail.com>
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>

3 files changed, 13 insertions, 29 deletions

diff --git a/src/location/maps/qgeocameratiles.cpp b/src/location/maps/qgeocameratiles.cpp
index 75d4512e..327d54b3 100644
--- a/src/location/maps/qgeocameratiles.cpp
+++ b/src/location/maps/qgeocameratiles.cpp
@@ -297,7 +297,7 @@ Frustum QGeoCameraTilesPrivate::createFrustum(double viewExpansion) const
         apertureSize = tan(QLocationUtils::radians(m_camera.fieldOfView()) * 0.5);
     QDoubleVector3D center = m_sideLength * QWebMercator::coordToMercator(m_camera.center());
 
-    double f = qMin(m_screenSize.width(), m_screenSize.height());
+    double f = m_screenSize.height();
 
     double z = std::pow(2.0, m_camera.zoomLevel() - m_intZoomLevel) * m_tileSize; // between 1 and 2 * m_tileSize
 
@@ -339,19 +339,12 @@ Frustum QGeoCameraTilesPrivate::createFrustum(double viewExpansion) const
     // This used to fix the (half) field of view at 45 degrees
     // half because this assumed that viewSize = 2*nearPlane x 2*nearPlane
     viewExpansion *= apertureSize;
-    if (aspectRatio > 1.0) {
-        hhn = viewExpansion * nearPlane;
-        hwn = hhn * aspectRatio;
 
-        hhf = viewExpansion * farPlane;
-        hwf = hhf * aspectRatio;
-    } else {
-        hwn = viewExpansion * nearPlane;
-        hhn = hwn / aspectRatio;
+    hhn = viewExpansion * nearPlane;
+    hwn = hhn * aspectRatio;
 
-        hwf = viewExpansion * farPlane;
-        hhf = hwf / aspectRatio;
-    }
+    hhf = viewExpansion * farPlane;
+    hwf = hhf * aspectRatio;
 
     QDoubleVector3D d = center - eye;
     d.normalize();
diff --git a/src/location/maps/qgeoprojection.cpp b/src/location/maps/qgeoprojection.cpp
index 81f3a947..4e5f1979 100644
--- a/src/location/maps/qgeoprojection.cpp
+++ b/src/location/maps/qgeoprojection.cpp
@@ -329,7 +329,7 @@ void QGeoProjectionWebMercator::setupCamera()
     m_sideLength = (1 << intZoomLevel) * defaultTileSize;
     m_center = m_centerMercator * m_sideLength;
 
-    double f = 1.0 * qMin(m_viewportWidth, m_viewportHeight);
+    double f = m_viewportHeight;
     double z = std::pow(2.0, m_cameraData.zoomLevel() - intZoomLevel) * defaultTileSize;
     double altitude = f / (2.0 * z);
     // Also in mercator space
@@ -402,16 +402,10 @@ void QGeoProjectionWebMercator::setupCamera()
 
     double aspectRatio = 1.0 * m_viewportWidth / m_viewportHeight;
 
-    m_halfWidth = m_aperture;
+    m_halfWidth = m_aperture * aspectRatio;
     m_halfHeight = m_aperture;
-    double verticalAperture = m_aperture;
-    if (aspectRatio > 1.0) {
-        m_halfWidth *= aspectRatio;
-    } else if (aspectRatio > 0.0 && aspectRatio < 1.0) {
-        m_halfHeight /= aspectRatio;
-        verticalAperture /= aspectRatio;
-    }
-    double verticalHalfFOV = QLocationUtils::degrees(atan(verticalAperture));
+
+    double verticalHalfFOV = QLocationUtils::degrees(atan(m_aperture));
 
     QDoubleMatrix4x4 cameraMatrix;
     cameraMatrix.lookAt(m_eye, m_center, m_up);
@@ -452,7 +446,7 @@ void QGeoProjectionWebMercator::setupCamera()
     double verticalEstateToSkip = 0;
     if (maxRayElevation < verticalHalfFOV) {
         maxHalfAperture = tan(QLocationUtils::radians(maxRayElevation));
-        verticalEstateToSkip = 1.0 - maxHalfAperture / verticalAperture;
+        verticalEstateToSkip = 1.0 - maxHalfAperture / m_aperture;
     }
 
     m_minimumUnprojectableY = verticalEstateToSkip * 0.5 * m_viewportHeight; // verticalEstateToSkip is relative to half aperture
diff --git a/src/location/maps/qgeotiledmapscene.cpp b/src/location/maps/qgeotiledmapscene.cpp
index 3711841d..d38eec39 100644
--- a/src/location/maps/qgeotiledmapscene.cpp
+++ b/src/location/maps/qgeotiledmapscene.cpp
@@ -350,7 +350,7 @@ void QGeoTiledMapScenePrivate::updateTileBounds(const QSet<QGeoTileSpec> &tiles)
 void QGeoTiledMapScenePrivate::setupCamera()
 {
     // NOTE: The following instruction is correct only because WebMercator is a square projection!
-    double f = 1.0 * qMin(m_screenSize.width(), m_screenSize.height());
+    double f = m_screenSize.height();
 
     // Using fraction of zoom level, z varies between [ m_tileSize , 2 * m_tileSize [
     double z = std::pow(2.0, m_cameraData.zoomLevel() - m_intZoomLevel) * m_tileSize;
@@ -431,11 +431,8 @@ void QGeoTiledMapScenePrivate::setupCamera()
     double aspectRatio = 1.0 * m_screenSize.width() / m_screenSize.height();
     float halfWidth = 1 * apertureSize;
     float halfHeight = 1 * apertureSize;
-    if (aspectRatio > 1.0) {
-        halfWidth *= aspectRatio;
-    } else if (aspectRatio > 0.0f && aspectRatio < 1.0f) {
-        halfHeight /= aspectRatio;
-    }
+    halfWidth *= aspectRatio;
+
     m_projectionMatrix.setToIdentity();
     m_projectionMatrix.frustum(-halfWidth, halfWidth, -halfHeight, halfHeight, nearPlane, farPlane);
 }