[core] Update shaders.

Implements 'icon-pitch-alignment' (issue #9345)
Fixes issue #9456 (map-aligned point label regression)

src/mbgl/layout/symbol_layout.cpp

@@ -75,10 +75,13 @@ SymbolLayout::SymbolLayout(const BucketParameters& parameters,
         }
     }
 
-    // If unspecified `text-pitch-alignment` inherits `text-rotation-alignment`
+    // If unspecified `*-pitch-alignment` inherits `*-rotation-alignment`
     if (layout.get<TextPitchAlignment>() == AlignmentType::Auto) {
         layout.get<TextPitchAlignment>() = layout.get<TextRotationAlignment>();
     }
+    if (layout.get<IconPitchAlignment>() == AlignmentType::Auto) {
+        layout.get<IconPitchAlignment>() = layout.get<IconRotationAlignment>();
+    }
 
     const bool hasText = has<TextField>(layout) && !layout.get<TextFont>().empty();
     const bool hasIcon = has<IconImage>(layout);

src/mbgl/programs/symbol_program.cpp

@@ -52,6 +52,11 @@ Values makeValues(const bool isText,
     const float pixelsToTileUnits = tile.id.pixelsToTileUnits(1.0, state.getZoom());
     const bool pitchWithMap = values.pitchAlignment == style::AlignmentType::Map;
     const bool rotateWithMap = values.rotationAlignment == style::AlignmentType::Map;
+    
+    // Line label rotation happens in `updateLineLabels`
+    // Pitched point labels are automatically rotated by the labelPlaneMatrix projection
+    // Unpitched point labels need to have their rotation applied after projection
+    const bool rotateInShader = rotateWithMap && !pitchWithMap && !alongLine;
 
     mat4 labelPlaneMatrix;
     if (alongLine) {
@@ -84,6 +89,8 @@ Values makeValues(const bool isText,
         uniforms::u_pitch::Value{ state.getPitch() },
         uniforms::u_pitch_with_map::Value{ pitchWithMap },
         uniforms::u_max_camera_distance::Value{ values.maxCameraDistance },
+        uniforms::u_rotate_symbol::Value{ rotateInShader },
+        uniforms::u_aspect_ratio::Value{ state.getSize().aspectRatio() },
         std::forward<Args>(args)...
     };
 }

src/mbgl/programs/symbol_program.hpp

@@ -41,6 +41,8 @@ MBGL_DEFINE_UNIFORM_SCALAR(bool, u_is_size_feature_constant);
 MBGL_DEFINE_UNIFORM_SCALAR(float, u_size_t);
 MBGL_DEFINE_UNIFORM_SCALAR(float, u_size);
 MBGL_DEFINE_UNIFORM_SCALAR(float, u_max_camera_distance);
+MBGL_DEFINE_UNIFORM_SCALAR(bool, u_rotate_symbol);
+MBGL_DEFINE_UNIFORM_SCALAR(float, u_aspect_ratio);
 } // namespace uniforms
 
 struct SymbolLayoutAttributes : gl::Attributes<
@@ -348,7 +350,9 @@ class SymbolIconProgram : public SymbolProgram<
         uniforms::u_camera_to_center_distance,
         uniforms::u_pitch,
         uniforms::u_pitch_with_map,
-        uniforms::u_max_camera_distance>,
+        uniforms::u_max_camera_distance,
+        uniforms::u_rotate_symbol,
+        uniforms::u_aspect_ratio>,
     style::IconPaintProperties>
 {
 public:
@@ -387,6 +391,8 @@ class SymbolSDFProgram : public SymbolProgram<
         uniforms::u_pitch,
         uniforms::u_pitch_with_map,
         uniforms::u_max_camera_distance,
+        uniforms::u_rotate_symbol,
+        uniforms::u_aspect_ratio,
         uniforms::u_gamma_scale,
         uniforms::u_is_halo>,
     PaintProperties>
@@ -409,6 +415,8 @@ public:
             uniforms::u_pitch,
             uniforms::u_pitch_with_map,            
             uniforms::u_max_camera_distance,
+            uniforms::u_rotate_symbol,
+            uniforms::u_aspect_ratio,
             uniforms::u_gamma_scale,
             uniforms::u_is_halo>,
         PaintProperties>;

src/mbgl/renderer/layers/render_symbol_layer.cpp

@@ -82,7 +82,7 @@ style::TextPaintProperties::PossiblyEvaluated RenderSymbolLayer::textPaintProper
 
 style::SymbolPropertyValues RenderSymbolLayer::iconPropertyValues(const style::SymbolLayoutProperties::PossiblyEvaluated& layout_) const {
     return style::SymbolPropertyValues {
-            layout_.get<style::IconRotationAlignment>(), // icon-pitch-alignment is not yet implemented; inherit the rotation alignment
+            layout_.get<style::IconPitchAlignment>(),
             layout_.get<style::IconRotationAlignment>(),
             layout_.get<style::IconKeepUpright>(),
             evaluated.get<style::IconTranslate>(),

src/mbgl/shaders/symbol_icon.cpp

@@ -19,6 +19,8 @@ uniform highp float u_size_t; // used to interpolate between zoom stops when siz
 uniform highp float u_size; // used when size is both zoom and feature constant
 uniform highp float u_camera_to_center_distance;
 uniform highp float u_pitch;
+uniform bool u_rotate_symbol;
+uniform highp float u_aspect_ratio;
 uniform highp float u_collision_y_stretch;
 
 
@@ -83,8 +85,19 @@ void main() {
 
     float fontScale = u_is_text ? size / 24.0 : size;
 
-    highp float angle_sin = sin(segment_angle);
-    highp float angle_cos = cos(segment_angle);
+    highp float symbol_rotation = 0.0;
+    if (u_rotate_symbol) {
+        // See comments in symbol_sdf.vertex
+        vec4 offsetProjectedPoint = u_matrix * vec4(a_pos + vec2(1, 0), 0, 1);
+
+        vec2 a = projectedPoint.xy / projectedPoint.w;
+        vec2 b = offsetProjectedPoint.xy / offsetProjectedPoint.w;
+
+        symbol_rotation = atan((b.y - a.y) / u_aspect_ratio, b.x - a.x);
+    }
+
+    highp float angle_sin = sin(segment_angle + symbol_rotation);
+    highp float angle_cos = cos(segment_angle + symbol_rotation);
     mat2 rotation_matrix = mat2(angle_cos, -1.0 * angle_sin, angle_sin, angle_cos);
 
     vec4 projected_pos = u_label_plane_matrix * vec4(a_projected_pos.xy, 0.0, 1.0);

src/mbgl/shaders/symbol_sdf.cpp

@@ -73,6 +73,8 @@ uniform mat4 u_gl_coord_matrix;
 uniform bool u_is_text;
 uniform bool u_pitch_with_map;
 uniform highp float u_pitch;
+uniform bool u_rotate_symbol;
+uniform highp float u_aspect_ratio;
 uniform highp float u_camera_to_center_distance;
 uniform highp float u_collision_y_stretch;
 
@@ -151,8 +153,21 @@ void main() {
 
     float fontScale = u_is_text ? size / 24.0 : size;
 
-    highp float angle_sin = sin(segment_angle);
-    highp float angle_cos = cos(segment_angle);
+    highp float symbol_rotation = 0.0;
+    if (u_rotate_symbol) {
+        // Point labels with 'rotation-alignment: map' are horizontal with respect to tile units
+        // To figure out that angle in projected space, we draw a short horizontal line in tile
+        // space, project it, and measure its angle in projected space.
+        vec4 offsetProjectedPoint = u_matrix * vec4(a_pos + vec2(1, 0), 0, 1);
+
+        vec2 a = projectedPoint.xy / projectedPoint.w;
+        vec2 b = offsetProjectedPoint.xy / offsetProjectedPoint.w;
+
+        symbol_rotation = atan((b.y - a.y) / u_aspect_ratio, b.x - a.x);
+    }
+
+    highp float angle_sin = sin(segment_angle + symbol_rotation);
+    highp float angle_cos = cos(segment_angle + symbol_rotation);
     mat2 rotation_matrix = mat2(angle_cos, -1.0 * angle_sin, angle_sin, angle_cos);
 
     vec4 projected_pos = u_label_plane_matrix * vec4(a_projected_pos.xy, 0.0, 1.0);

src/mbgl/style/layers/symbol_layer.cpp

@@ -332,6 +332,22 @@ void SymbolLayer::setIconOffset(DataDrivenPropertyValue<std::array<float, 2>> va
     baseImpl = std::move(impl_);
     observer->onLayerChanged(*this);
 }
+PropertyValue<AlignmentType> SymbolLayer::getDefaultIconPitchAlignment() {
+    return IconPitchAlignment::defaultValue();
+}
+
+PropertyValue<AlignmentType> SymbolLayer::getIconPitchAlignment() const {
+    return impl().layout.get<IconPitchAlignment>();
+}
+
+void SymbolLayer::setIconPitchAlignment(PropertyValue<AlignmentType> value) {
+    if (value == getIconPitchAlignment())
+        return;
+    auto impl_ = mutableImpl();
+    impl_->layout.get<IconPitchAlignment>() = value;
+    baseImpl = std::move(impl_);
+    observer->onLayerChanged(*this);
+}
 PropertyValue<AlignmentType> SymbolLayer::getDefaultTextPitchAlignment() {
     return TextPitchAlignment::defaultValue();
 }

src/mbgl/style/layers/symbol_layer_properties.hpp

@@ -87,6 +87,11 @@ struct IconOffset : DataDrivenLayoutProperty<std::array<float, 2>> {
     static std::array<float, 2> defaultValue() { return {{ 0, 0 }}; }
 };
 
+struct IconPitchAlignment : LayoutProperty<AlignmentType> {
+    static constexpr const char * key = "icon-pitch-alignment";
+    static AlignmentType defaultValue() { return AlignmentType::Auto; }
+};
+
 struct TextPitchAlignment : LayoutProperty<AlignmentType> {
     static constexpr const char * key = "text-pitch-alignment";
     static AlignmentType defaultValue() { return AlignmentType::Auto; }
@@ -254,6 +259,7 @@ class SymbolLayoutProperties : public Properties<
     IconPadding,
     IconKeepUpright,
     IconOffset,
+    IconPitchAlignment,
     TextPitchAlignment,
     TextRotationAlignment,
     TextField,