update shaders and create symbol opacity buffer

13 files changed, 68 insertions, 75 deletions

diff --git a/src/mbgl/layout/symbol_layout.cpp b/src/mbgl/layout/symbol_layout.cpp
index 97806d05c2..017188cbf9 100644
--- a/src/mbgl/layout/symbol_layout.cpp
+++ b/src/mbgl/layout/symbol_layout.cpp
@@ -478,7 +478,7 @@ std::unique_ptr<SymbolBucket> SymbolLayout::place(CollisionTile& collisionTile)
 
                 for (const auto& symbol : symbolInstance.glyphQuads) {
                     addSymbol(
-                        bucket->text, sizeData, symbol, placementZoom,
+                        bucket->text, sizeData, symbol,
                         keepUpright, textPlacement, symbolInstance.anchor, bucket->text.placedSymbols.back());
                 }
             }
@@ -492,7 +492,7 @@ std::unique_ptr<SymbolBucket> SymbolLayout::place(CollisionTile& collisionTile)
                 bucket->icon.placedSymbols.emplace_back(symbolInstance.anchor.point, symbolInstance.anchor.segment, sizeData.min, sizeData.max,
                         symbolInstance.iconOffset, placementZoom, false, symbolInstance.line);
                 addSymbol(
-                    bucket->icon, sizeData, *symbolInstance.iconQuad, placementZoom,
+                    bucket->icon, sizeData, *symbolInstance.iconQuad,
                     keepUpright, iconPlacement, symbolInstance.anchor, bucket->icon.placedSymbols.back());
             }
         }
@@ -514,7 +514,6 @@ template <typename Buffer>
 void SymbolLayout::addSymbol(Buffer& buffer,
                              const Range<float> sizeData,
                              const SymbolQuad& symbol,
-                             const float placementZoom,
                              const bool keepUpright,
                              const style::SymbolPlacementType placement,
                              const Anchor& labelAnchor,
@@ -548,11 +547,17 @@ void SymbolLayout::addSymbol(Buffer& buffer,
     buffer.vertices.emplace_back(SymbolLayoutAttributes::vertex(labelAnchor.point, bl, symbol.glyphOffset.y, tex.x, tex.y + tex.h, sizeData));
     buffer.vertices.emplace_back(SymbolLayoutAttributes::vertex(labelAnchor.point, br, symbol.glyphOffset.y, tex.x + tex.w, tex.y + tex.h, sizeData));
     
-    auto dynamicVertex = SymbolDynamicLayoutAttributes::vertex(labelAnchor.point, 0, placementZoom);
+    auto dynamicVertex = SymbolDynamicLayoutAttributes::vertex(labelAnchor.point, 0);
     buffer.dynamicVertices.emplace_back(dynamicVertex);
     buffer.dynamicVertices.emplace_back(dynamicVertex);
     buffer.dynamicVertices.emplace_back(dynamicVertex);
     buffer.dynamicVertices.emplace_back(dynamicVertex);
+    
+    auto opacityVertex = SymbolOpacityAttributes::vertex(1.0, 1.0); // TODO
+    buffer.opacityVertices.emplace_back(opacityVertex);
+    buffer.opacityVertices.emplace_back(opacityVertex);
+    buffer.opacityVertices.emplace_back(opacityVertex);
+    buffer.opacityVertices.emplace_back(opacityVertex);
 
     // add the two triangles, referencing the four coordinates we just inserted.
     buffer.triangles.emplace_back(index + 0, index + 1, index + 2);
diff --git a/src/mbgl/layout/symbol_layout.hpp b/src/mbgl/layout/symbol_layout.hpp
index 90f5b3c91d..c5026040cf 100644
--- a/src/mbgl/layout/symbol_layout.hpp
+++ b/src/mbgl/layout/symbol_layout.hpp
@@ -61,7 +61,6 @@ private:
     void addSymbol(Buffer&,
                    const Range<float> sizeData,
                    const SymbolQuad&,
-                   float scale,
                    const bool keepUpright,
                    const style::SymbolPlacementType,
                    const Anchor& labelAnchor,
diff --git a/src/mbgl/layout/symbol_projection.cpp b/src/mbgl/layout/symbol_projection.cpp
index 377c8ea5b2..6b1dbf8fac 100644
--- a/src/mbgl/layout/symbol_projection.cpp
+++ b/src/mbgl/layout/symbol_projection.cpp
@@ -121,9 +121,9 @@ namespace mbgl {
         return inPaddedViewport;
     }
 
-    void addDynamicAttributes(const Point<float>& anchorPoint, const float angle, const float placementZoom,
+    void addDynamicAttributes(const Point<float>& anchorPoint, const float angle,
             gl::VertexVector<SymbolDynamicLayoutAttributes::Vertex>& dynamicVertexArray) {
-        auto dynamicVertex = SymbolDynamicLayoutAttributes::vertex(anchorPoint, angle, placementZoom);
+        auto dynamicVertex = SymbolDynamicLayoutAttributes::vertex(anchorPoint, angle);
         dynamicVertexArray.emplace_back(dynamicVertex);
         dynamicVertexArray.emplace_back(dynamicVertex);
         dynamicVertexArray.emplace_back(dynamicVertex);
@@ -133,7 +133,7 @@ namespace mbgl {
     void hideGlyphs(size_t numGlyphs, gl::VertexVector<SymbolDynamicLayoutAttributes::Vertex>& dynamicVertexArray) {
         const Point<float> offscreenPoint = { -INFINITY, -INFINITY };
         for (size_t i = 0; i < numGlyphs; i++) {
-            addDynamicAttributes(offscreenPoint, 0, 25, dynamicVertexArray);
+            addDynamicAttributes(offscreenPoint, 0, dynamicVertexArray);
         }
     }
 
@@ -339,7 +339,7 @@ namespace mbgl {
         }
 
         for (auto& placedGlyph : placedGlyphs) {
-            addDynamicAttributes(placedGlyph.point, placedGlyph.angle, symbol.placementZoom, dynamicVertexArray);
+            addDynamicAttributes(placedGlyph.point, placedGlyph.angle, dynamicVertexArray);
         }
         
         return PlacementResult::OK;
diff --git a/src/mbgl/programs/attributes.hpp b/src/mbgl/programs/attributes.hpp
index d023ec7d83..459de23f41 100644
--- a/src/mbgl/programs/attributes.hpp
+++ b/src/mbgl/programs/attributes.hpp
@@ -30,6 +30,7 @@ MBGL_DEFINE_ATTRIBUTE(int16_t, 2, a_anchor_pos);
 MBGL_DEFINE_ATTRIBUTE(uint16_t, 2, a_texture_pos);
 MBGL_DEFINE_ATTRIBUTE(int16_t,  3, a_normal);
 MBGL_DEFINE_ATTRIBUTE(uint16_t, 1, a_edgedistance);
+MBGL_DEFINE_ATTRIBUTE(uint8_t, 1, a_fade_opacity);
 
 template <typename T, std::size_t N>
 struct a_data {
diff --git a/src/mbgl/programs/symbol_program.cpp b/src/mbgl/programs/symbol_program.cpp
index 58174ff8a7..7aded08809 100644
--- a/src/mbgl/programs/symbol_program.cpp
+++ b/src/mbgl/programs/symbol_program.cpp
@@ -82,9 +82,8 @@ Values makeValues(const bool isText,
         uniforms::u_extrude_scale::Value{ extrudeScale },
         uniforms::u_texsize::Value{ texsize },
         uniforms::u_texture::Value{ 0 },
-        uniforms::u_fadetexture::Value{ 1 },
+        uniforms::u_fade_change::Value{ 1 },
         uniforms::u_is_text::Value{ isText },
-        uniforms::u_collision_y_stretch::Value{ tile.tile.yStretch() },
         uniforms::u_camera_to_center_distance::Value{ state.getCameraToCenterDistance() },
         uniforms::u_pitch::Value{ state.getPitch() },
         uniforms::u_pitch_with_map::Value{ pitchWithMap },
diff --git a/src/mbgl/programs/symbol_program.hpp b/src/mbgl/programs/symbol_program.hpp
index a7abf94f56..7616205791 100644
--- a/src/mbgl/programs/symbol_program.hpp
+++ b/src/mbgl/programs/symbol_program.hpp
@@ -75,18 +75,24 @@ struct SymbolLayoutAttributes : gl::Attributes<
 };
 
 struct SymbolDynamicLayoutAttributes : gl::Attributes<attributes::a_projected_pos> {
-    static Vertex vertex(Point<float> anchorPoint, float labelAngle, float labelminzoom) {
+    static Vertex vertex(Point<float> anchorPoint, float labelAngle) {
         return Vertex {
             {{
                  anchorPoint.x,
                  anchorPoint.y,
-                 static_cast<float>(mbgl::attributes::packUint8Pair(
-                         static_cast<uint8_t>(std::fmod(labelAngle + 2 * M_PI, 2 * M_PI) / (2 * M_PI) * 255),
-                         static_cast<uint8_t>(labelminzoom * 10)))
+                 labelAngle
              }}
         };
     }
 };
+
+struct SymbolOpacityAttributes : gl::Attributes<attributes::a_fade_opacity> {
+    static Vertex vertex(float targetOpacity, float opacity) {
+        return Vertex {
+            {{ static_cast<uint8_t>((static_cast<uint8_t>(opacity * 127) << 1) | static_cast<uint8_t>(targetOpacity == 1.0 ? 1 : 0)) }}
+        };
+    }
+};
     
 struct ZoomEvaluatedSize {
     bool isZoomConstant;
@@ -276,7 +282,7 @@ public:
     using LayoutAttributes = LayoutAttrs;
     using LayoutVertex = typename LayoutAttributes::Vertex;
     
-    using LayoutAndSizeAttributes = gl::ConcatenateAttributes<LayoutAttributes, SymbolDynamicLayoutAttributes>;
+    using LayoutAndSizeAttributes = gl::ConcatenateAttributes<LayoutAttributes, gl::ConcatenateAttributes<SymbolDynamicLayoutAttributes, SymbolOpacityAttributes>>;
 
     using PaintProperties = PaintProps;
     using PaintPropertyBinders = typename PaintProperties::Binders;
@@ -310,6 +316,7 @@ public:
               const UniformValues& uniformValues,
               const gl::VertexBuffer<LayoutVertex>& layoutVertexBuffer,
               const gl::VertexBuffer<SymbolDynamicLayoutAttributes::Vertex>& dynamicLayoutVertexBuffer,
+              const gl::VertexBuffer<SymbolOpacityAttributes::Vertex>& opacityVertexBuffer,
               const SymbolSizeBinder& symbolSizeBinder,
               const gl::IndexBuffer<DrawMode>& indexBuffer,
               const SegmentVector<Attributes>& segments,
@@ -323,6 +330,7 @@ public:
 
         typename Attributes::Bindings allAttributeBindings = LayoutAttributes::bindings(layoutVertexBuffer)
             .concat(SymbolDynamicLayoutAttributes::bindings(dynamicLayoutVertexBuffer))
+            .concat(SymbolOpacityAttributes::bindings(opacityVertexBuffer))
             .concat(paintPropertyBinders.attributeBindings(currentProperties));
 
         for (auto& segment : segments) {
@@ -359,9 +367,8 @@ class SymbolIconProgram : public SymbolProgram<
         uniforms::u_extrude_scale,
         uniforms::u_texsize,
         uniforms::u_texture,
-        uniforms::u_fadetexture,
+        uniforms::u_fade_change,
         uniforms::u_is_text,
-        uniforms::u_collision_y_stretch,
         uniforms::u_camera_to_center_distance,
         uniforms::u_pitch,
         uniforms::u_pitch_with_map,
@@ -399,9 +406,8 @@ class SymbolSDFProgram : public SymbolProgram<
         uniforms::u_extrude_scale,
         uniforms::u_texsize,
         uniforms::u_texture,
-        uniforms::u_fadetexture,
+        uniforms::u_fade_change,
         uniforms::u_is_text,
-        uniforms::u_collision_y_stretch,
         uniforms::u_camera_to_center_distance,
         uniforms::u_pitch,
         uniforms::u_pitch_with_map,
@@ -423,9 +429,8 @@ public:
             uniforms::u_extrude_scale,
             uniforms::u_texsize,
             uniforms::u_texture,
-            uniforms::u_fadetexture,
+            uniforms::u_fade_change,
             uniforms::u_is_text,
-            uniforms::u_collision_y_stretch,
             uniforms::u_camera_to_center_distance,
             uniforms::u_pitch,
             uniforms::u_pitch_with_map,            
diff --git a/src/mbgl/programs/uniforms.hpp b/src/mbgl/programs/uniforms.hpp
index 285d243251..184f42e504 100644
--- a/src/mbgl/programs/uniforms.hpp
+++ b/src/mbgl/programs/uniforms.hpp
@@ -36,6 +36,7 @@ MBGL_DEFINE_UNIFORM_SCALAR(Size, u_world);
 MBGL_DEFINE_UNIFORM_SCALAR(Size, u_texsize);
 MBGL_DEFINE_UNIFORM_SCALAR(bool, u_pitch_with_map);
 MBGL_DEFINE_UNIFORM_SCALAR(float, u_camera_to_center_distance);
+MBGL_DEFINE_UNIFORM_SCALAR(float, u_fade_change);
 
 MBGL_DEFINE_UNIFORM_VECTOR(float, 2, u_extrude_scale);
 
diff --git a/src/mbgl/renderer/buckets/symbol_bucket.cpp b/src/mbgl/renderer/buckets/symbol_bucket.cpp
index a3f71f1f6e..ee225b0c6c 100644
--- a/src/mbgl/renderer/buckets/symbol_bucket.cpp
+++ b/src/mbgl/renderer/buckets/symbol_bucket.cpp
@@ -38,12 +38,14 @@ void SymbolBucket::upload(gl::Context& context) {
     if (hasTextData()) {
         text.vertexBuffer = context.createVertexBuffer(std::move(text.vertices));
         text.dynamicVertexBuffer = context.createVertexBuffer(std::move(text.dynamicVertices), gl::BufferUsage::StreamDraw);
+        text.opacityVertexBuffer = context.createVertexBuffer(std::move(text.opacityVertices), gl::BufferUsage::StreamDraw);
         text.indexBuffer = context.createIndexBuffer(std::move(text.triangles));
     }
 
     if (hasIconData()) {
         icon.vertexBuffer = context.createVertexBuffer(std::move(icon.vertices));
         icon.dynamicVertexBuffer = context.createVertexBuffer(std::move(icon.dynamicVertices), gl::BufferUsage::StreamDraw);
+        icon.opacityVertexBuffer = context.createVertexBuffer(std::move(text.opacityVertices), gl::BufferUsage::StreamDraw);
         icon.indexBuffer = context.createIndexBuffer(std::move(icon.triangles));
     }
 
diff --git a/src/mbgl/renderer/buckets/symbol_bucket.hpp b/src/mbgl/renderer/buckets/symbol_bucket.hpp
index a918628e52..2e91f02ea1 100644
--- a/src/mbgl/renderer/buckets/symbol_bucket.hpp
+++ b/src/mbgl/renderer/buckets/symbol_bucket.hpp
@@ -70,12 +70,14 @@ public:
     struct TextBuffer {
         gl::VertexVector<SymbolLayoutVertex> vertices;
         gl::VertexVector<SymbolDynamicLayoutAttributes::Vertex> dynamicVertices;
+        gl::VertexVector<SymbolOpacityAttributes::Vertex> opacityVertices;
         gl::IndexVector<gl::Triangles> triangles;
         SegmentVector<SymbolTextAttributes> segments;
         std::vector<PlacedSymbol> placedSymbols;
 
         optional<gl::VertexBuffer<SymbolLayoutVertex>> vertexBuffer;
         optional<gl::VertexBuffer<SymbolDynamicLayoutAttributes::Vertex>> dynamicVertexBuffer;
+        optional<gl::VertexBuffer<SymbolOpacityAttributes::Vertex>> opacityVertexBuffer;
         optional<gl::IndexBuffer<gl::Triangles>> indexBuffer;
     } text;
     
@@ -84,6 +86,7 @@ public:
     struct IconBuffer {
         gl::VertexVector<SymbolLayoutVertex> vertices;
         gl::VertexVector<SymbolDynamicLayoutAttributes::Vertex> dynamicVertices;
+        gl::VertexVector<SymbolOpacityAttributes::Vertex> opacityVertices;
         gl::IndexVector<gl::Triangles> triangles;
         SegmentVector<SymbolIconAttributes> segments;
         std::vector<PlacedSymbol> placedSymbols;
@@ -91,6 +94,7 @@ public:
 
         optional<gl::VertexBuffer<SymbolLayoutVertex>> vertexBuffer;
         optional<gl::VertexBuffer<SymbolDynamicLayoutAttributes::Vertex>> dynamicVertexBuffer;
+        optional<gl::VertexBuffer<SymbolOpacityAttributes::Vertex>> opacityVertexBuffer;
         optional<gl::IndexBuffer<gl::Triangles>> indexBuffer;
     } icon;
 
diff --git a/src/mbgl/renderer/layers/render_symbol_layer.cpp b/src/mbgl/renderer/layers/render_symbol_layer.cpp
index e3d2da94a7..95e0ad7c5e 100644
--- a/src/mbgl/renderer/layers/render_symbol_layer.cpp
+++ b/src/mbgl/renderer/layers/render_symbol_layer.cpp
@@ -104,6 +104,7 @@ void RenderSymbolLayer::render(PaintParameters& parameters, RenderSource*) {
                 std::move(uniformValues),
                 *buffers.vertexBuffer,
                 *buffers.dynamicVertexBuffer,
+                *buffers.opacityVertexBuffer,
                 *symbolSizeBinder,
                 *buffers.indexBuffer,
                 buffers.segments,
diff --git a/src/mbgl/shaders/preludes.cpp b/src/mbgl/shaders/preludes.cpp
index feb185a684..6baa488a10 100644
--- a/src/mbgl/shaders/preludes.cpp
+++ b/src/mbgl/shaders/preludes.cpp
@@ -34,6 +34,10 @@ vec2 unpack_float(const float packedValue) {
     return vec2(v0, packedIntValue - v0 * 256);
 }
 
+vec2 unpack_opacity(const float packedOpacity) {
+    int intOpacity = int(packedOpacity) / 2;
+    return vec2(float(intOpacity) / 127.0, mod(packedOpacity, 2.0));
+}
 
 // To minimize the number of attributes needed, we encode a 4-component
 // color into a pair of floats (i.e. a vec2) as follows:
diff --git a/src/mbgl/shaders/symbol_icon.cpp b/src/mbgl/shaders/symbol_icon.cpp
index 1e96194738..f5c2bbe22d 100644
--- a/src/mbgl/shaders/symbol_icon.cpp
+++ b/src/mbgl/shaders/symbol_icon.cpp
@@ -12,6 +12,7 @@ const float PI = 3.141592653589793;
 attribute vec4 a_pos_offset;
 attribute vec4 a_data;
 attribute vec3 a_projected_pos;
+attribute float a_fade_opacity;
 
 uniform bool u_is_size_zoom_constant;
 uniform bool u_is_size_feature_constant;
@@ -21,7 +22,7 @@ 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;
+uniform float u_fade_change;
 
 
 #ifndef HAS_UNIFORM_u_opacity
@@ -43,7 +44,7 @@ uniform bool u_pitch_with_map;
 uniform vec2 u_texsize;
 
 varying vec2 v_tex;
-varying vec2 v_fade_tex;
+varying float v_fade_opacity;
 
 void main() {
     
@@ -60,9 +61,7 @@ void main() {
     vec2 a_tex = a_data.xy;
     vec2 a_size = a_data.zw;
 
-    highp vec2 angle_labelminzoom = unpack_float(a_projected_pos[2]);
-    highp float segment_angle = -angle_labelminzoom[0] / 255.0 * 2.0 * PI;
-    mediump float a_labelminzoom = angle_labelminzoom[1];
+    highp float segment_angle = -a_projected_pos[2];
 
     float size;
     if (!u_is_size_zoom_constant && !u_is_size_feature_constant) {
@@ -106,19 +105,14 @@ void main() {
     gl_Position = u_gl_coord_matrix * vec4(projected_pos.xy / projected_pos.w + rotation_matrix * (a_offset / 64.0 * fontScale), 0.0, 1.0);
 
     v_tex = a_tex / u_texsize;
-    // See comments in symbol_sdf.vertex
-    highp float incidence_stretch  = camera_to_anchor_distance / (u_camera_to_center_distance * cos(u_pitch));
-    highp float collision_adjustment = max(1.0, incidence_stretch / u_collision_y_stretch);
-
-    highp float collision_perspective_ratio = 1.0 + 0.5*((camera_to_anchor_distance / u_camera_to_center_distance) - 1.0);
-    highp float perspective_zoom_adjust = floor(log2(collision_perspective_ratio * collision_adjustment) * 10.0);
-    v_fade_tex = vec2((a_labelminzoom + perspective_zoom_adjust) / 255.0, 0.0);
+    vec2 fade_opacity = unpack_opacity(a_fade_opacity);
+    float fade_change = fade_opacity[1] > 0.5 ? u_fade_change : -u_fade_change;
+    v_fade_opacity = max(0.0, min(1.0, fade_opacity[0] + fade_change));
 }
 
 )MBGL_SHADER";
 const char* symbol_icon::fragmentSource = R"MBGL_SHADER(
 uniform sampler2D u_texture;
-uniform sampler2D u_fadetexture;
 
 
 #ifndef HAS_UNIFORM_u_opacity
@@ -129,7 +123,7 @@ uniform lowp float u_opacity;
 
 
 varying vec2 v_tex;
-varying vec2 v_fade_tex;
+varying float v_fade_opacity;
 
 void main() {
     
@@ -138,7 +132,7 @@ void main() {
 #endif
 
 
-    lowp float alpha = texture2D(u_fadetexture, v_fade_tex).a * opacity;
+    lowp float alpha = opacity * v_fade_opacity;
     gl_FragColor = texture2D(u_texture, v_tex) * alpha;
 
 #ifdef OVERDRAW_INSPECTOR
diff --git a/src/mbgl/shaders/symbol_sdf.cpp b/src/mbgl/shaders/symbol_sdf.cpp
index a4427f31ab..441eaf7aac 100644
--- a/src/mbgl/shaders/symbol_sdf.cpp
+++ b/src/mbgl/shaders/symbol_sdf.cpp
@@ -12,6 +12,7 @@ const float PI = 3.141592653589793;
 attribute vec4 a_pos_offset;
 attribute vec4 a_data;
 attribute vec3 a_projected_pos;
+attribute float a_fade_opacity;
 
 // contents of a_size vary based on the type of property value
 // used for {text,icon}-size.
@@ -81,12 +82,12 @@ 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;
+uniform float u_fade_change;
 
 uniform vec2 u_texsize;
 
-varying vec4 v_data0;
-varying vec2 v_data1;
+varying vec2 v_data0;
+varying vec3 v_data1;
 
 void main() {
     
@@ -131,9 +132,7 @@ void main() {
     vec2 a_tex = a_data.xy;
     vec2 a_size = a_data.zw;
 
-    highp vec2 angle_labelminzoom = unpack_float(a_projected_pos[2]);
-    highp float segment_angle = -angle_labelminzoom[0] / 255.0 * 2.0 * PI;
-    mediump float a_labelminzoom = angle_labelminzoom[1];
+    highp float segment_angle = -a_projected_pos[2];
     float size;
 
     if (!u_is_size_zoom_constant && !u_is_size_feature_constant) {
@@ -185,31 +184,12 @@ void main() {
     float gamma_scale = gl_Position.w;
 
     vec2 tex = a_tex / u_texsize;
-    // incidence_stretch is the ratio of how much y space a label takes up on a tile while drawn perpendicular to the viewport vs
-    //  how much space it would take up if it were drawn flat on the tile
-    // Using law of sines, camera_to_anchor/sin(ground_angle) = camera_to_center/sin(incidence_angle)
-    // sin(incidence_angle) = 1/incidence_stretch
-    // Incidence angle 90 -> head on, sin(incidence_angle) = 1, no incidence stretch
-    // Incidence angle 1 -> very oblique, sin(incidence_angle) =~ 0, lots of incidence stretch
-    // ground_angle = u_pitch + PI/2 -> sin(ground_angle) = cos(u_pitch)
-    // This 2D calculation is only exactly correct when gl_Position.x is in the center of the viewport,
-    //  but it's a close enough approximation for our purposes
-    highp float incidence_stretch  = camera_to_anchor_distance / (u_camera_to_center_distance * cos(u_pitch));
-    // incidence_stretch only applies to the y-axis, but without re-calculating the collision tile, we can't
-    // adjust the size of only one axis. So, we do a crude approximation at placement time to get the aspect ratio
-    // about right, and then do the rest of the adjustment here: there will be some extra padding on the x-axis,
-    // but hopefully not too much.
-    // Never make the adjustment less than 1.0: instead of allowing collisions on the x-axis, be conservative on
-    // the y-axis.
-    highp float collision_adjustment = max(1.0, incidence_stretch / u_collision_y_stretch);
-
-    // Floor to 1/10th zoom to dodge precision issues that can cause partially hidden labels
-    highp float collision_perspective_ratio = 1.0 + 0.5*((camera_to_anchor_distance / u_camera_to_center_distance) - 1.0);
-    highp float perspective_zoom_adjust = floor(log2(collision_perspective_ratio * collision_adjustment) * 10.0);
-    vec2 fade_tex = vec2((a_labelminzoom + perspective_zoom_adjust) / 255.0, 0.0);
-
-    v_data0 = vec4(tex.x, tex.y, fade_tex.x, fade_tex.y);
-    v_data1 = vec2(gamma_scale, size);
+    vec2 fade_opacity = unpack_opacity(a_fade_opacity);
+    float fade_change = fade_opacity[1] > 0.5 ? u_fade_change : -u_fade_change;
+    float interpolated_fade_opacity = max(0.0, min(1.0, fade_opacity[0] + fade_change));
+
+    v_data0 = vec2(tex.x, tex.y);
+    v_data1 = vec3(gamma_scale, size, interpolated_fade_opacity);
 }
 
 )MBGL_SHADER";
@@ -255,12 +235,11 @@ uniform lowp float u_halo_blur;
 
 
 uniform sampler2D u_texture;
-uniform sampler2D u_fadetexture;
 uniform highp float u_gamma_scale;
 uniform bool u_is_text;
 
-varying vec4 v_data0;
-varying vec2 v_data1;
+varying vec2 v_data0;
+varying vec3 v_data1;
 
 void main() {
     
@@ -290,9 +269,9 @@ void main() {
 
 
     vec2 tex = v_data0.xy;
-    vec2 fade_tex = v_data0.zw;
     float gamma_scale = v_data1.x;
     float size = v_data1.y;
+    float fade_opacity = v_data1[2];
 
     float fontScale = u_is_text ? size / 24.0 : size;
 
@@ -306,11 +285,10 @@ void main() {
     }
 
     lowp float dist = texture2D(u_texture, tex).a;
-    lowp float fade_alpha = texture2D(u_fadetexture, fade_tex).a;
     highp float gamma_scaled = gamma * gamma_scale;
-    highp float alpha = smoothstep(buff - gamma_scaled, buff + gamma_scaled, dist) * fade_alpha;
+    highp float alpha = smoothstep(buff - gamma_scaled, buff + gamma_scaled, dist);
 
-    gl_FragColor = color * (alpha * opacity);
+    gl_FragColor = color * (alpha * opacity * fade_opacity);
 
 #ifdef OVERDRAW_INSPECTOR
     gl_FragColor = vec4(1.0);