playcanvas/build/playcanvas.dbg/src/platform/graphics/webgpu/webgpu-clear-renderer.js

Open-source WebGL/WebGPU 3D engine for the web

import { Debug } from '../../../core/debug.js';
import { UniformBufferFormat, UniformFormat } from '../uniform-buffer-format.js';
import { BlendState } from '../blend-state.js';
import { BINDGROUP_MESH_UB, BINDGROUP_MESH, CLEARFLAG_COLOR, CLEARFLAG_DEPTH, CLEARFLAG_STENCIL, PRIMITIVE_TRISTRIP, SHADERLANGUAGE_WGSL, UNIFORMTYPE_VEC4, UNIFORMTYPE_FLOAT } from '../constants.js';
import { Shader } from '../shader.js';
import { DynamicBindGroup } from '../bind-group.js';
import { UniformBuffer } from '../uniform-buffer.js';
import { DebugGraphics } from '../debug-graphics.js';
import { DepthState } from '../depth-state.js';

const primitive = {
    type: PRIMITIVE_TRISTRIP,
    base: 0,
    baseVertex: 0,
    count: 4,
    indexed: false
};
/**
 * A WebGPU helper class implementing a viewport clear operation. When rendering to a texture,
 * the whole surface can be cleared using loadOp, but if only a viewport needs to be cleared, or if
 * it needs to be cleared later during the rendering, this need to be achieved by rendering a quad.
 * This class renders a full-screen quad, and expects the viewport / scissor to be set up to clip
 * it to only required area.
 *
 * @ignore
 */ class WebgpuClearRenderer {
    destroy() {
        this.shader.destroy();
        this.shader = null;
        this.uniformBuffer.destroy();
        this.uniformBuffer = null;
    }
    clear(device, renderTarget, options, defaultOptions) {
        options = options || defaultOptions;
        const flags = options.flags ?? defaultOptions.flags;
        if (flags !== 0) {
            DebugGraphics.pushGpuMarker(device, 'CLEAR-RENDERER');
            // dynamic bind group for the UB
            const { uniformBuffer, dynamicBindGroup } = this;
            uniformBuffer.startUpdate(dynamicBindGroup);
            device.setBindGroup(BINDGROUP_MESH_UB, dynamicBindGroup.bindGroup, dynamicBindGroup.offsets);
            // not using mesh bind group
            device.setBindGroup(BINDGROUP_MESH, device.emptyBindGroup);
            // setup clear color
            let blendState;
            if (flags & CLEARFLAG_COLOR && (renderTarget.colorBuffer || renderTarget.impl.assignedColorTexture)) {
                const color = options.color ?? defaultOptions.color;
                this.colorData.set(color);
                blendState = BlendState.NOBLEND;
            } else {
                blendState = BlendState.NOWRITE;
            }
            uniformBuffer.set('color', this.colorData);
            // setup depth clear
            let depthState;
            if (flags & CLEARFLAG_DEPTH && renderTarget.depth) {
                const depth = options.depth ?? defaultOptions.depth;
                uniformBuffer.set('depth', depth);
                depthState = DepthState.WRITEDEPTH;
            } else {
                uniformBuffer.set('depth', 1);
                depthState = DepthState.NODEPTH;
            }
            // setup stencil clear
            if (flags & CLEARFLAG_STENCIL && renderTarget.stencil) {
                Debug.warnOnce('ClearRenderer does not support stencil clear at the moment');
            }
            uniformBuffer.endUpdate();
            device.setDrawStates(blendState, depthState);
            // render 4 vertices without vertex buffer
            device.setShader(this.shader);
            device.draw(primitive);
            DebugGraphics.popGpuMarker(device);
        }
    }
    constructor(device){
        // shader that can write out color and depth values
        const code = `

            struct ub_mesh {
                color : vec4f,
                depth: f32
            }

            @group(2) @binding(0) var<uniform> ubMesh : ub_mesh;

            var<private> pos : array<vec2f, 4> = array<vec2f, 4>(
                vec2(-1.0, 1.0), vec2(1.0, 1.0),
                vec2(-1.0, -1.0), vec2(1.0, -1.0)
            );

            struct VertexOutput {
                @builtin(position) position : vec4f
            }

            @vertex
            fn vertexMain(@builtin(vertex_index) vertexIndex : u32) -> VertexOutput {
                var output : VertexOutput;
                output.position = vec4(pos[vertexIndex], ubMesh.depth, 1.0);
                return output;
            }

            @fragment
            fn fragmentMain() -> @location(0) vec4f {
                return ubMesh.color;
            }
        `;
        this.shader = new Shader(device, {
            name: 'WebGPUClearRendererShader',
            shaderLanguage: SHADERLANGUAGE_WGSL,
            vshader: code,
            fshader: code
        });
        // uniforms
        this.uniformBuffer = new UniformBuffer(device, new UniformBufferFormat(device, [
            new UniformFormat('color', UNIFORMTYPE_VEC4),
            new UniformFormat('depth', UNIFORMTYPE_FLOAT)
        ]), false);
        this.dynamicBindGroup = new DynamicBindGroup();
        // uniform data
        this.colorData = new Float32Array(4);
    }
}

export { WebgpuClearRenderer };