set further near plane to fix depth precision for deckgl

src/geo/transform.js

@@ -537,9 +537,18 @@ class Transform {
         // Add a bit extra to avoid precision problems when a fragment's distance is exactly `furthestDistance`
         const farZ = furthestDistance * 1.01;
 
+        // The larger the value of nearZ is
+        // - the more depth precision is available for features (good)
+        // - clipping starts appearing sooner when the camera is close to 3d features (bad)
+        //
+        // Smaller values worked well for mapbox-gl-js but deckgl was encountering precision issues
+        // when rendering it's layers using custom layers. This value was experimentally chosen and
+        // seems to solve z-fighting issues in deckgl while not clipping buildings too close to the camera.
+        const nearZ = this.height / 50;
+
         // matrix for conversion from location to GL coordinates (-1 .. 1)
         let m = new Float64Array(16);
-        mat4.perspective(m, this._fov, this.width / this.height, 1, farZ);
+        mat4.perspective(m, this._fov, this.width / this.height, nearZ, farZ);
 
         mat4.scale(m, m, [1, -1, 1]);
         mat4.translate(m, m, [0, 0, -this.cameraToCenterDistance]);

src/ui/map.js

@@ -1,5 +1,6 @@
 // @flow
 
+import { version } from '../../package.json';
 import { extend, bindAll, warnOnce, uniqueId } from '../util/util';
 import browser from '../util/browser';
 import window from '../util/window';
@@ -1942,6 +1943,17 @@ class Map extends Camera {
     _setCacheLimits(limit: number, checkThreshold: number) {
         setCacheLimits(limit, checkThreshold);
     }
+
+    /**
+     * The version of Mapbox GL JS in use as specified in package.json, CHANGELOG.md, and the GitHub release.
+     *
+     * @name version
+     * @instance
+     * @memberof Map
+     * @var {string} version
+     */
+
+    get version(): string { return version; }
 }
 
 export default Map;

test/unit/ui/marker.test.js

@@ -424,8 +424,8 @@ test('Marker with draggable:true moves to new position in response to a mouse-tr
     simulate.mouseup(el);
 
     const endPos = map.project(marker.getLngLat());
-    t.equal(Math.floor(endPos.x), startPos.x + 10);
-    t.equal(Math.floor(endPos.y), startPos.y + 10);
+    t.equal(Math.round(endPos.x), startPos.x + 10);
+    t.equal(Math.round(endPos.y), startPos.y + 10);
 
     map.remove();
     t.end();