6 files changed, 148 insertions, 100 deletions

diff --git a/src/mbgl/shaders/collision_box.cpp b/src/mbgl/shaders/collision_box.cpp
index 07fa94e338..9d11640bf4 100644
--- a/src/mbgl/shaders/collision_box.cpp
+++ b/src/mbgl/shaders/collision_box.cpp
@@ -10,77 +10,50 @@ const char* collision_box::vertexSource = R"MBGL_SHADER(
 attribute vec2 a_pos;
 attribute vec2 a_anchor_pos;
 attribute vec2 a_extrude;
-attribute vec2 a_data;
+attribute vec2 a_placed;
 
 uniform mat4 u_matrix;
-uniform float u_scale;
-uniform float u_pitch;
-uniform float u_collision_y_stretch;
+uniform vec2 u_extrude_scale;
 uniform float u_camera_to_center_distance;
 
-varying float v_max_zoom;
-varying float v_placement_zoom;
-varying float v_perspective_zoom_adjust;
-varying vec2 v_fade_tex;
+varying float v_placed;
+varying float v_notUsed;
 
 void main() {
     vec4 projectedPoint = u_matrix * vec4(a_anchor_pos, 0, 1);
     highp float camera_to_anchor_distance = projectedPoint.w;
-    highp float collision_perspective_ratio = 1.0 + 0.5 * ((camera_to_anchor_distance / u_camera_to_center_distance) - 1.0);
+    highp float collision_perspective_ratio = 0.5 + 0.5 * (u_camera_to_center_distance / camera_to_anchor_distance);
 
-    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);
+    gl_Position = u_matrix * vec4(a_pos, 0.0, 1.0);
+    gl_Position.xy += a_extrude * u_extrude_scale * gl_Position.w * collision_perspective_ratio;
 
-    gl_Position = u_matrix * vec4(a_pos + a_extrude * collision_perspective_ratio * collision_adjustment / u_scale, 0.0, 1.0);
-
-    v_max_zoom = a_data.x;
-    v_placement_zoom = a_data.y;
-
-    v_perspective_zoom_adjust = floor(log2(collision_perspective_ratio * collision_adjustment) * 10.0);
-    v_fade_tex = vec2((v_placement_zoom + v_perspective_zoom_adjust) / 255.0, 0.0);
+    v_placed = a_placed.x;
+    v_notUsed = a_placed.y;
 }
 
 )MBGL_SHADER";
 const char* collision_box::fragmentSource = R"MBGL_SHADER(
-uniform float u_zoom;
-// u_maxzoom is derived from the maximum scale considered by the CollisionTile
-// Labels with placement zoom greater than this value will not be placed,
-// regardless of perspective effects.
-uniform float u_maxzoom;
-uniform sampler2D u_fadetexture;
-
-// v_max_zoom is a collision-box-specific value that controls when line-following
-// collision boxes are used.
-varying float v_max_zoom;
-varying float v_placement_zoom;
-varying float v_perspective_zoom_adjust;
-varying vec2 v_fade_tex;
+
+varying float v_placed;
+varying float v_notUsed;
 
 void main() {
 
     float alpha = 0.5;
 
-    // Green = no collisions, label is showing
-    gl_FragColor = vec4(0.0, 1.0, 0.0, 1.0) * alpha;
+    // Red = collision, hide label
+    gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0) * alpha;
 
-    // Red = collision, label hidden
-    if (texture2D(u_fadetexture, v_fade_tex).a < 1.0) {
-        gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0) * alpha;
+    // Blue = no collision, label is showing
+    if (v_placed > 0.5) {
+        gl_FragColor = vec4(0.0, 0.0, 1.0, 0.5) * alpha;
     }
 
-    // Faded black = this collision box is not used at this zoom (for curved labels)
-    if (u_zoom >= v_max_zoom + v_perspective_zoom_adjust) {
-        gl_FragColor = vec4(0.0, 0.0, 0.0, 1.0) * alpha * 0.25;
-    }
-
-    // Faded blue = the placement scale for this label is beyond the CollisionTile
-    // max scale, so it's impossible for this label to show without collision detection
-    // being run again (the label's glyphs haven't even been added to the symbol bucket)
-    if (v_placement_zoom >= u_maxzoom) {
-        gl_FragColor = vec4(0.0, 0.0, 1.0, 1.0) * alpha * 0.2;
+    if (v_notUsed > 0.5) {
+        // This box not used, fade it out
+        gl_FragColor *= .1;
     }
 }
-
 )MBGL_SHADER";
 
 } // namespace shaders
diff --git a/src/mbgl/shaders/collision_circle.cpp b/src/mbgl/shaders/collision_circle.cpp
new file mode 100644
index 0000000000..1e85d99a33
--- /dev/null
+++ b/src/mbgl/shaders/collision_circle.cpp
@@ -0,0 +1,83 @@
+// NOTE: DO NOT CHANGE THIS FILE. IT IS AUTOMATICALLY GENERATED.
+
+#include <mbgl/shaders/collision_circle.hpp>
+
+namespace mbgl {
+namespace shaders {
+
+const char* collision_circle::name = "collision_circle";
+const char* collision_circle::vertexSource = R"MBGL_SHADER(
+attribute vec2 a_pos;
+attribute vec2 a_anchor_pos;
+attribute vec2 a_extrude;
+attribute vec2 a_placed;
+
+uniform mat4 u_matrix;
+uniform vec2 u_extrude_scale;
+uniform float u_camera_to_center_distance;
+
+varying float v_placed;
+varying float v_notUsed;
+varying float v_radius;
+
+varying vec2 v_extrude;
+varying vec2 v_extrude_scale;
+
+void main() {
+    vec4 projectedPoint = u_matrix * vec4(a_anchor_pos, 0, 1);
+    highp float camera_to_anchor_distance = projectedPoint.w;
+    highp float collision_perspective_ratio = 0.5 + 0.5 * (camera_to_anchor_distance / u_camera_to_center_distance);
+
+    gl_Position = u_matrix * vec4(a_pos, 0.0, 1.0);
+
+    highp float padding_factor = 1.2; // Pad the vertices slightly to make room for anti-alias blur
+    gl_Position.xy += a_extrude * u_extrude_scale * padding_factor * gl_Position.w / collision_perspective_ratio;
+
+    v_placed = a_placed.x;
+    v_notUsed = a_placed.y;
+    v_radius = abs(a_extrude.y); // We don't pitch the circles, so both units of the extrusion vector are equal in magnitude to the radius
+
+    v_extrude = a_extrude * padding_factor;
+    v_extrude_scale = u_extrude_scale * u_camera_to_center_distance / collision_perspective_ratio;
+}
+
+)MBGL_SHADER";
+const char* collision_circle::fragmentSource = R"MBGL_SHADER(
+
+varying float v_placed;
+varying float v_notUsed;
+varying float v_radius;
+varying vec2 v_extrude;
+varying vec2 v_extrude_scale;
+
+void main() {
+    float alpha = 0.5;
+
+    // Red = collision, hide label
+    vec4 color = vec4(1.0, 0.0, 0.0, 1.0) * alpha;
+
+    // Blue = no collision, label is showing
+    if (v_placed > 0.5) {
+        color = vec4(0.0, 0.0, 1.0, 0.5) * alpha;
+    }
+
+    if (v_notUsed > 0.5) {
+        // This box not used, fade it out
+        color *= .2;
+    }
+
+    float extrude_scale_length = length(v_extrude_scale);
+    float extrude_length = length(v_extrude) * extrude_scale_length;
+    float stroke_width = 3.0;
+    float radius = v_radius * extrude_scale_length;
+
+    float distance_to_edge = abs(extrude_length - radius);
+    float opacity_t = smoothstep(-stroke_width, 0.0, -distance_to_edge);
+
+    gl_FragColor = opacity_t * color;
+}
+
+)MBGL_SHADER";
+
+} // namespace shaders
+} // namespace mbgl
diff --git a/src/mbgl/shaders/collision_circle.hpp b/src/mbgl/shaders/collision_circle.hpp
new file mode 100644
index 0000000000..12b1bcd445
--- /dev/null
+++ b/src/mbgl/shaders/collision_circle.hpp
@@ -0,0 +1,16 @@
+// NOTE: DO NOT CHANGE THIS FILE. IT IS AUTOMATICALLY GENERATED.
+
+#pragma once
+
+namespace mbgl {
+namespace shaders {
+
+class collision_circle {
+public:
+    static const char* name;
+    static const char* vertexSource;
+    static const char* fragmentSource;
+};
+
+} // namespace shaders
+} // namespace mbgl
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);