From 73d9f26d03810854c36a96b252885353f8ba81ce Mon Sep 17 00:00:00 2001
From: Aleksandar Stojiljkovic <aleksandar.stojiljkovic@mapbox.com>
Date: Tue, 23 Jul 2019 17:19:52 +0300
Subject: [core] Limit pitch based on edge insets. Fix max Z calculation in
 getProjMatrix.

Patch partly fixes #15163 in a way that it doesn't allow loading tens of thousands of tiles and attempt to show area above horizon:

Limit pitch based on edge insets. It is not too bad - current limit of 60 degrees stays active until center of perspective is moved towards the bottom, to 84% of screen height. The plan is to split removal of 60 degrees limit to follow up patch.

Fix max Z calculation in getProjMatrix. TransformState::getProjMatrix calculation of farZ was complex with possibility to lead to negative z values. Replacing it with simpler, precise calculation:
furthestDistance = cameraToCenterDistance / (1 - tanFovAboveCenter * std::tan(getPitch()));

TransformState::getProjMatrix calculation of farZ was an aproximation. Replacing it with simpler, but precise calculation.

Related to: #15163
---
 test/map/transform.test.cpp   |  3 +++
 test/util/tile_cover.test.cpp | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+)

(limited to 'test')

diff --git a/test/map/transform.test.cpp b/test/map/transform.test.cpp
index 3d37312b17..84fdb06b21 100644
--- a/test/map/transform.test.cpp
+++ b/test/map/transform.test.cpp
@@ -9,6 +9,7 @@ using namespace mbgl;
 
 TEST(Transform, InvalidZoom) {
     Transform transform;
+    transform.resize({1, 1});
 
     ASSERT_DOUBLE_EQ(0, transform.getLatLng().latitude());
     ASSERT_DOUBLE_EQ(0, transform.getLatLng().longitude());
@@ -56,6 +57,7 @@ TEST(Transform, InvalidZoom) {
 
 TEST(Transform, InvalidBearing) {
     Transform transform;
+    transform.resize({1, 1});
 
     ASSERT_DOUBLE_EQ(0, transform.getLatLng().latitude());
     ASSERT_DOUBLE_EQ(0, transform.getLatLng().longitude());
@@ -78,6 +80,7 @@ TEST(Transform, InvalidBearing) {
 
 TEST(Transform, IntegerZoom) {
     Transform transform;
+    transform.resize({1, 1});
 
     auto checkIntegerZoom = [&transform](uint8_t zoomInt, double zoom) {
         transform.jumpTo(CameraOptions().withZoom(zoom));
diff --git a/test/util/tile_cover.test.cpp b/test/util/tile_cover.test.cpp
index 3fc7681520..e35e6e2e99 100644
--- a/test/util/tile_cover.test.cpp
+++ b/test/util/tile_cover.test.cpp
@@ -43,6 +43,41 @@ TEST(TileCover, Pitch) {
               util::tileCover(transform.getState(), 2));
 }
 
+TEST(TileCover, PitchOverAllowedByContentInsets) {
+    Transform transform;
+    transform.resize({ 512, 512 });
+
+    transform.jumpTo(CameraOptions().withCenter(LatLng { 0.1, -0.1 }).withPadding(EdgeInsets { 376, 0, 0, 0 })
+                                    .withZoom(8.0).withBearing(45.0).withPitch(60.0));
+    // Top padding of 376 leads to capped pitch. See Transform::getMaxPitchForEdgeInsets.
+    EXPECT_LE(transform.getPitch() + 0.001, util::DEG2RAD * 60);
+
+    EXPECT_EQ((std::vector<UnwrappedTileID>{
+        { 3, 4, 3 }, { 3, 3, 3 }, { 3, 4, 4 }, { 3, 3, 4 }, { 3, 4, 2 }, { 3, 5, 3 }, { 3, 5, 2 }
+    }),
+              util::tileCover(transform.getState(), 3));
+}
+
+TEST(TileCover, PitchWithLargerResultSet) {
+    Transform transform;
+    transform.resize({ 1024, 768 });
+
+    // The values used here triggered the regression with left and right edge
+    // selection in tile_cover.cpp scanSpans.
+    transform.jumpTo(CameraOptions().withCenter(LatLng { 0.1, -0.1 }).withPadding(EdgeInsets { 400, 0, 0, 0 })
+                                    .withZoom(5).withBearing(-142.2630000003529176).withPitch(60.0));
+
+    auto cover = util::tileCover(transform.getState(), 5);
+    // Returned vector has above 100 elements, we check first 16 as there is a
+    // plan to return lower LOD for distant tiles.
+    EXPECT_EQ((std::vector<UnwrappedTileID> {
+        { 5, 15, 16 }, { 5, 15, 17 }, { 5, 14, 16 }, { 5, 14, 17 },
+        { 5, 16, 16 }, { 5, 16, 17 }, { 5, 15, 15 }, { 5, 14, 15 },
+        { 5, 15, 18 }, { 5, 14, 18 }, { 5, 16, 15 }, { 5, 13, 16 },
+        { 5, 13, 17 }, { 5, 16, 18 }, { 5, 13, 18 }, { 5, 15, 19 }
+    }), (std::vector<UnwrappedTileID> { cover.begin(), cover.begin() + 16}) );
+}
+
 TEST(TileCover, WorldZ1) {
     EXPECT_EQ((std::vector<UnwrappedTileID>{
         { 1, 0, 0 }, { 1, 0, 1 }, { 1, 1, 0 }, { 1, 1, 1 },
-- 
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