Expose projection matrix parameters

src/geo/transform.ts

@@ -58,6 +58,8 @@ export class Transform {
     _constraining: boolean;
     _posMatrixCache: {[_: string]: mat4};
     _alignedPosMatrixCache: {[_: string]: mat4};
+    _farZ: number;
+    _nearZ: number;
 
     constructor(minZoom?: number, maxZoom?: number, minPitch?: number, maxPitch?: number, renderWorldCopies?: boolean) {
         this.tileSize = 512; // constant
@@ -870,7 +872,7 @@ export class Transform {
         // Calculate z distance of the farthest fragment that should be rendered.
         // Add a bit extra to avoid precision problems when a fragment's distance is exactly `furthestDistance`
         const topHalfMinDistance = Math.min(topHalfSurfaceDistance, topHalfSurfaceDistanceHorizon);
-        const farZ = (Math.cos(Math.PI / 2 - this._pitch) * topHalfMinDistance + lowestPlane) * 1.01;
+        this._farZ = (Math.cos(Math.PI / 2 - this._pitch) * topHalfMinDistance + lowestPlane) * 1.01;
 
         // The larger the value of nearZ is
         // - the more depth precision is available for features (good)
@@ -879,11 +881,11 @@ export class Transform {
         // Other values work for mapbox-gl-js but deckgl was encountering precision issues
         // when rendering 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;
+        this._nearZ = this.height / 50;
 
         // matrix for conversion from location to clip space(-1 .. 1)
         m = new Float64Array(16) as any;
-        mat4.perspective(m, this._fov, this.width / this.height, nearZ, farZ);
+        mat4.perspective(m, this._fov, this.width / this.height, this._nearZ, this._farZ);
 
         // Apply center of perspective offset
         m[8] = -offset.x * 2 / this.width;

src/render/draw_custom.ts

@@ -36,7 +36,7 @@ export function drawCustom(painter: Painter, sourceCache: SourceCache, layer: Cu
 
         context.setDepthMode(depthMode);
 
-        implementation.render(context.gl, painter.transform.customLayerMatrix());
+        implementation.render(context.gl, painter.transform.customLayerMatrix(), painter.transform);
 
         context.setDirty();
         painter.setBaseState();

src/style/style_layer/custom_style_layer.ts

@@ -2,6 +2,7 @@ import {StyleLayer} from '../style_layer';
 import type {Map} from '../../ui/map';
 import {mat4} from 'gl-matrix';
 import {LayerSpecification} from '@maplibre/maplibre-gl-style-spec';
+import {Transform} from '../../geo/transform';
 
 /**
  * @param gl - The map's gl context.
@@ -11,8 +12,10 @@ import {LayerSpecification} from '@maplibre/maplibre-gl-style-spec';
  * the `renderingMode` is `"3d"`, the z coordinate is conformal. A box with identical x, y, and z
  * lengths in mercator units would be rendered as a cube. {@link MercatorCoordinate.fromLngLat}
  * can be used to project a `LngLat` to a mercator coordinate.
+ * @param transform - The map's transform object. It contains properties and methods used to calculate
+ * the map's matrix transformations.
  */
-type CustomRenderMethod = (gl: WebGLRenderingContext|WebGL2RenderingContext, matrix: mat4) => void;
+type CustomRenderMethod = (gl: WebGLRenderingContext|WebGL2RenderingContext, matrix: mat4, transform: Transform) => void;
 
 /**
  * Interface for custom style layers. This is a specification for