[core, ios] replace `altitude` with `fov`

ported from -js: eb6c6596c6a7a61363d30356674e0002153b1d19

`altitude` was a terribly-named variable that was used to indirectly
control the fov. This should eliminate some confusion.

`altitude` was equivalent to `cameraToCenterDistance / height`

2 files changed, 4 insertions, 4 deletions

diff --git a/src/mbgl/programs/line_program.cpp b/src/mbgl/programs/line_program.cpp
index 2cadaa6c11..cd53337c10 100644
--- a/src/mbgl/programs/line_program.cpp
+++ b/src/mbgl/programs/line_program.cpp
@@ -25,7 +25,7 @@ Values makeValues(const LinePaintProperties::Evaluated& properties,
 
     // calculate how much longer the real world distance is at the top of the screen
     // than at the middle of the screen.
-    float topedgelength = std::sqrt(std::pow(state.getSize().height, 2.0f) / 4.0f  * (1.0f + std::pow(state.getAltitude(), 2.0f)));
+    float topedgelength = std::sqrt(std::pow(state.getSize().height, 2.0f) / 4.0f  * (1.0f + std::pow(state.getCameraToCenterDistance(), 2.0f)));
     float x = state.getSize().height / 2.0f * std::tan(state.getPitch());
 
     return Values {
diff --git a/src/mbgl/programs/symbol_program.cpp b/src/mbgl/programs/symbol_program.cpp
index 71b45ad4fc..d609dada8d 100644
--- a/src/mbgl/programs/symbol_program.cpp
+++ b/src/mbgl/programs/symbol_program.cpp
@@ -23,8 +23,8 @@ Values makeValues(const style::SymbolPropertyValues& values,
         extrudeScale.fill(tile.id.pixelsToTileUnits(1, state.getZoom()) * scale);
     } else {
         extrudeScale = {{
-            pixelsToGLUnits[0] * scale * state.getAltitude(),
-            pixelsToGLUnits[1] * scale * state.getAltitude()
+            pixelsToGLUnits[0] * scale * state.getCameraToCenterDistance(),
+            pixelsToGLUnits[1] * scale * state.getCameraToCenterDistance()
         }};
     }
 
@@ -77,7 +77,7 @@ static SymbolSDFProgram::UniformValues makeSDFValues(const style::SymbolProperty
     const float gammaBase = 0.105 * values.sdfScale / values.paintSize / pixelRatio;
     const float gammaScale = (values.pitchAlignment == AlignmentType::Map
         ? 1.0 / std::cos(state.getPitch())
-        : 1.0) / state.getAltitude();
+        : 1.0) / state.getCameraToCenterDistance();
 
     return makeValues<SymbolSDFProgram::UniformValues>(
         values,