Prevent creation of unused depth renderbuffer attachments (mapbox#9377)

* Remove unused depth renderbuffer

Should save width * height * 2 bytes of uncompressed buffer memory

* Prevent creation of unused depth renderbuffers

Add option to allow not creating extra renderbuffers
Refer https://www.khronos.org/registry/webgl/specs/latest/1.0/\#6.8 for supported attachment variants
Should save the hillshade offscreen buffer width * height * 2 bytes of uncompressed gpu memory

* Fix lint

* Update src/gl/framebuffer.js

Co-Authored-By: Vladimir Agafonkin <agafonkin@gmail.com>

Co-authored-by: Vladimir Agafonkin <agafonkin@gmail.com>

src/gl/context.js

@@ -203,8 +203,8 @@ class Context {
         return rbo;
     }
 
-    createFramebuffer(width: number, height: number) {
-        return new Framebuffer(this, width, height);
+    createFramebuffer(width: number, height: number, hasDepth: boolean) {
+        return new Framebuffer(this, width, height, hasDepth);
     }
 
     clear({color, depth}: ClearArgs) {

src/gl/framebuffer.js

@@ -1,5 +1,6 @@
 // @flow
 import {ColorAttachment, DepthAttachment} from './value';
+import assert from 'assert';
 
 import type Context from './context';
 
@@ -11,15 +12,18 @@ class Framebuffer {
     colorAttachment: ColorAttachment;
     depthAttachment: DepthAttachment;
 
-    constructor(context: Context, width: number, height: number) {
+    constructor(context: Context, width: number, height: number, hasDepth: boolean) {
         this.context = context;
         this.width = width;
         this.height = height;
         const gl = context.gl;
         const fbo = this.framebuffer = gl.createFramebuffer();
 
         this.colorAttachment = new ColorAttachment(context, fbo);
-        this.depthAttachment = new DepthAttachment(context, fbo);
+        if (hasDepth) {
+            this.depthAttachment = new DepthAttachment(context, fbo);
+        }
+        assert(gl.checkFramebufferStatus(gl.FRAMEBUFFER) === gl.FRAMEBUFFER_COMPLETE);
     }
 
     destroy() {
@@ -28,8 +32,10 @@ class Framebuffer {
         const texture = this.colorAttachment.get();
         if (texture) gl.deleteTexture(texture);
 
-        const renderbuffer = this.depthAttachment.get();
-        if (renderbuffer) gl.deleteRenderbuffer(renderbuffer);
+        if (this.depthAttachment) {
+            const renderbuffer = this.depthAttachment.get();
+            if (renderbuffer) gl.deleteRenderbuffer(renderbuffer);
+        }
 
         gl.deleteFramebuffer(this.framebuffer);
     }

src/render/draw_heatmap.js

@@ -87,7 +87,7 @@ function bindFramebuffer(context, painter, layer) {
         gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
         gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
 
-        fbo = layer.heatmapFbo = context.createFramebuffer(painter.width / 4, painter.height / 4);
+        fbo = layer.heatmapFbo = context.createFramebuffer(painter.width / 4, painter.height / 4, false);
 
         bindTextureToFramebuffer(context, painter, texture, fbo);
 

src/render/draw_hillshade.js

@@ -90,7 +90,7 @@ function prepareHillshade(painter, tile, layer, sourceMaxZoom, depthMode, stenci
             const renderTexture = new Texture(context, {width: tileSize, height: tileSize, data: null}, gl.RGBA);
             renderTexture.bind(gl.LINEAR, gl.CLAMP_TO_EDGE);
 
-            fbo = tile.fbo = context.createFramebuffer(tileSize, tileSize);
+            fbo = tile.fbo = context.createFramebuffer(tileSize, tileSize, true);
             fbo.colorAttachment.set(renderTexture.texture);
         }
 

src/render/painter.js

@@ -92,8 +92,6 @@ class Painter {
     emptyProgramConfiguration: ProgramConfiguration;
     width: number;
     height: number;
-    depthRbo: WebGLRenderbuffer;
-    depthRboNeedsClear: boolean;
     tileExtentBuffer: VertexBuffer;
     tileExtentSegments: SegmentVector;
     debugBuffer: VertexBuffer;
@@ -136,8 +134,6 @@ class Painter {
         this.numSublayers = SourceCache.maxUnderzooming + SourceCache.maxOverzooming + 1;
         this.depthEpsilon = 1 / Math.pow(2, 16);
 
-        this.depthRboNeedsClear = true;
-
         this.crossTileSymbolIndex = new CrossTileSymbolIndex();
 
         this.gpuTimers = {};
@@ -148,8 +144,6 @@ class Painter {
      * for a new width and height value.
      */
     resize(width: number, height: number) {
-        const gl = this.context.gl;
-
         this.width = width * browser.devicePixelRatio;
         this.height = height * browser.devicePixelRatio;
         this.context.viewport.set([0, 0, this.width, this.height]);
@@ -159,11 +153,6 @@ class Painter {
                 this.style._layers[layerId].resize();
             }
         }
-
-        if (this.depthRbo) {
-            gl.deleteRenderbuffer(this.depthRbo);
-            this.depthRbo = null;
-        }
     }
 
     setup() {
@@ -402,7 +391,6 @@ class Painter {
         // framebuffer, and then save those for rendering back to the map
         // later: in doing this we avoid doing expensive framebuffer restores.
         this.renderPass = 'offscreen';
-        this.depthRboNeedsClear = true;
 
         for (const layerId of layerIds) {
             const layer = this.style._layers[layerId];
@@ -483,14 +471,6 @@ class Painter {
         this.context.setDefault();
     }
 
-    setupOffscreenDepthRenderbuffer(): void {
-        const context = this.context;
-        // All of the 3D textures will use the same depth renderbuffer.
-        if (!this.depthRbo) {
-            this.depthRbo = context.createRenderbuffer(context.gl.DEPTH_COMPONENT16, this.width, this.height);
-        }
-    }
-
     renderLayer(painter: Painter, sourceCache: SourceCache, layer: StyleLayer, coords: Array<OverscaledTileID>) {
         if (layer.isHidden(this.transform.zoom)) return;
         if (layer.type !== 'background' && layer.type !== 'custom' && !coords.length) return;