1 files changed, 28 insertions, 42 deletions
diff --git a/src/mbgl/shaders/symbol_icon.cpp b/src/mbgl/shaders/symbol_icon.cpp
index 8960e02c28..cb00cdad05 100644
--- a/src/mbgl/shaders/symbol_icon.cpp
+++ b/src/mbgl/shaders/symbol_icon.cpp
@@ -7,17 +7,16 @@ namespace shaders {
 
 const char* symbol_icon::name = "symbol_icon";
 const char* symbol_icon::vertexSource = R"MBGL_SHADER(
+const float PI = 3.141592653589793;
+
 attribute vec4 a_pos_offset;
-attribute vec2 a_label_pos;
 attribute vec4 a_data;
+attribute vec3 a_projected_pos;
 
-// icon-size data (see symbol_sdf.vertex.glsl for more)
-attribute vec3 a_size;
 uniform bool u_is_size_zoom_constant;
 uniform bool u_is_size_feature_constant;
 uniform highp float u_size_t; // used to interpolate between zoom stops when size is a composite function
 uniform highp float u_size; // used when size is both zoom and feature constant
-uniform highp float u_layout_size; // used when size is feature constant
 uniform highp float u_camera_to_center_distance;
 uniform highp float u_pitch;
 uniform highp float u_collision_y_stretch;
@@ -31,13 +30,12 @@ varying lowp float opacity;
 uniform lowp float u_opacity;
 #endif
 
-// matrix is for the vertex position.
 uniform mat4 u_matrix;
+uniform mat4 u_label_plane_matrix;
+uniform mat4 u_gl_coord_matrix;
 
 uniform bool u_is_text;
-uniform highp float u_zoom;
-uniform bool u_rotate_with_map;
-uniform vec2 u_extrude_scale;
+uniform bool u_pitch_with_map;
 
 uniform vec2 u_texsize;
 
@@ -56,61 +54,49 @@ void main() {
     vec2 a_offset = a_pos_offset.zw;
 
     vec2 a_tex = a_data.xy;
-    highp vec2 label_data = unpack_float(a_data[2]);
-    highp float a_labelminzoom = label_data[0];
-    highp vec2 a_zoom = unpack_float(a_data[3]);
-    highp float a_minzoom = a_zoom[0];
-    highp float a_maxzoom = a_zoom[1];
+    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];
 
     float size;
-    // In order to accommodate placing labels around corners in
-    // symbol-placement: line, each glyph in a label could have multiple
-    // "quad"s only one of which should be shown at a given zoom level.
-    // The min/max zoom assigned to each quad is based on the font size at
-    // the vector tile's zoom level, which might be different than at the
-    // currently rendered zoom level if text-size is zoom-dependent.
-    // Thus, we compensate for this difference by calculating an adjustment
-    // based on the scale of rendered text size relative to layout text size.
-    highp float layoutSize;
     if (!u_is_size_zoom_constant && !u_is_size_feature_constant) {
         size = mix(a_size[0], a_size[1], u_size_t) / 10.0;
-        layoutSize = a_size[2] / 10.0;
     } else if (u_is_size_zoom_constant && !u_is_size_feature_constant) {
         size = a_size[0] / 10.0;
-        layoutSize = size;
     } else if (!u_is_size_zoom_constant && u_is_size_feature_constant) {
         size = u_size;
-        layoutSize = u_layout_size;
     } else {
         size = u_size;
-        layoutSize = u_size;
     }
 
-    float fontScale = u_is_text ? size / 24.0 : size;
+    vec4 projectedPoint = u_matrix * vec4(a_pos, 0, 1);
+    highp float camera_to_anchor_distance = projectedPoint.w;
+    // See comments in symbol_sdf.vertex
+    highp float distance_ratio = u_pitch_with_map ?
+        camera_to_anchor_distance / u_camera_to_center_distance :
+        u_camera_to_center_distance / camera_to_anchor_distance;
+    highp float perspective_ratio = 0.5 + 0.5 * distance_ratio;
 
-    highp float zoomAdjust = log2(size / layoutSize);
-    highp float adjustedZoom = (u_zoom - zoomAdjust) * 10.0;
-    // result: z = 0 if a_minzoom <= adjustedZoom < a_maxzoom, and 1 otherwise
-    highp float z = 2.0 - step(a_minzoom, adjustedZoom) - (1.0 - step(a_maxzoom, adjustedZoom));
+    size *= perspective_ratio;
 
-    vec4 projectedPoint = u_matrix * vec4(a_label_pos, 0, 1);
-    highp float camera_to_anchor_distance = projectedPoint.w;
-    highp float perspective_ratio = 1.0 + 0.5*((camera_to_anchor_distance / u_camera_to_center_distance) - 1.0);
+    float fontScale = u_is_text ? size / 24.0 : size;
 
-    vec2 extrude = fontScale * u_extrude_scale * perspective_ratio * (a_offset / 64.0);
-    if (u_rotate_with_map) {
-        gl_Position = u_matrix * vec4(a_pos + extrude, 0, 1);
-        gl_Position.z += z * gl_Position.w;
-    } else {
-        gl_Position = u_matrix * vec4(a_pos, 0, 1) + vec4(extrude, 0, 0);
-    }
+    highp float angle_sin = sin(segment_angle);
+    highp float angle_cos = cos(segment_angle);
+    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);
+    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 perspective_zoom_adjust = log2(perspective_ratio * collision_adjustment) * 10.0;
+    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);
 }