Make debug collision boxes take account of text-pitch-scale

src/render/draw_collision_debug.js

@@ -24,6 +24,12 @@ function drawCollisionDebug(painter, sourceCache, layer, coords) {
         gl.uniform1f(program.u_zoom, painter.transform.zoom * 10);
         gl.uniform1f(program.u_maxzoom, (tile.coord.z + 1) * 10);
 
+        gl.uniform1f(program.u_collision_y_stretch, tile.collisionTile.yStretch);
+        gl.uniform1f(program.u_pitch, painter.transform.pitch / 360 * 2 * Math.PI);
+        gl.uniform1f(program.u_camera_to_center_distance, painter.transform.cameraToCenterDistance);
+        // TODO: Hook up to `text-pitch-scale` and `icon-pitch-scale` properties
+        gl.uniform1f(program.u_pitch_scale, 0.0);
+
         for (const segment of buffers.segments) {
             segment.vaos[layer.id].bind(gl, program, buffers.layoutVertexBuffer, buffers.elementBuffer, null, segment.vertexOffset);
             gl.drawElements(gl.LINES, segment.primitiveLength * 2, gl.UNSIGNED_SHORT, segment.primitiveOffset * 2 * 2);

src/shaders/collision_box.fragment.glsl

@@ -3,6 +3,7 @@ uniform float u_maxzoom;
 
 varying float v_max_zoom;
 varying float v_placement_zoom;
+varying float v_perspective_zoom_adjust;
 
 void main() {
 
@@ -21,9 +22,9 @@ void main() {
         gl_FragColor = vec4(0.0, 0.0, 0.0, 1.0) * alpha;
     }
 
-    if (v_placement_zoom >= u_maxzoom) {
     // Blue = this collision box will not be placed at tile zoom + 1
     //  e.g. The only way to show this is overzooming
+    if (v_placement_zoom >= u_maxzoom + v_perspective_zoom_adjust) {
         gl_FragColor = vec4(0.0, 0.0, 1.0, 1.0) * alpha;
     }
 }

src/shaders/collision_box.vertex.glsl

@@ -4,13 +4,27 @@ attribute vec2 a_data;
 
 uniform mat4 u_matrix;
 uniform float u_scale;
+uniform float u_pitch;
+uniform float u_collision_y_stretch;
+uniform float u_pitch_scale;
+uniform float u_camera_to_center_distance;
 
 varying float v_max_zoom;
 varying float v_placement_zoom;
+varying float v_perspective_zoom_adjust;
 
 void main() {
-    gl_Position = u_matrix * vec4(a_pos + a_extrude / u_scale, 0.0, 1.0);
+    vec4 projectedPoint = u_matrix * vec4(a_pos, 0, 1);
+    highp float camera_to_anchor_distance = projectedPoint.w;
+    highp float perspective_ratio = 1.0 + (1.0 - u_pitch_scale)*((camera_to_anchor_distance / u_camera_to_center_distance) - 1.0);;
 
-    v_max_zoom = a_data.x;
-    v_placement_zoom = a_data.y;
+    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 + a_extrude * perspective_ratio * collision_adjustment / u_scale, 0.0, 1.0);
+
+    v_perspective_zoom_adjust = log2(perspective_ratio * collision_adjustment)*10.0;
+
+    v_max_zoom = a_data.x + v_perspective_zoom_adjust;
+    v_placement_zoom = a_data.y + v_perspective_zoom_adjust;
 }