GPURenderPassEncoder: draw() method

{{APIRef("WebGPU API")}}{{SecureContext_Header}}{{AvailableInWorkers}}

The draw() method of the {{domxref("GPURenderPassEncoder")}} interface draws primitives based on the vertex buffers provided by {{domxref("GPURenderPassEncoder.setVertexBuffer", "setVertexBuffer()")}}.

Syntax

draw(vertexCount)
draw(vertexCount, instanceCount)
draw(vertexCount, instanceCount, firstVertex)
draw(vertexCount, instanceCount, firstVertex, firstInstance)

Parameters

• vertexCount
  • : A number defining the number of vertices to draw.
• instanceCount {{optional_inline}}
  • : A number defining the number of instances to draw. If omitted, instanceCount defaults to 1.
• firstVertex {{optional_inline}}
  • : A number defining the offset into the vertex buffers, in vertices, to begin drawing from. If omitted, firstVertex defaults to 0.
• firstInstance {{optional_inline}}
  • : A number defining the first instance to draw. If omitted, firstInstance defaults to 0.

Return value

None ({{jsxref("Undefined")}}).

Examples

In our basic render demo, several commands are recorded via a {{domxref("GPUCommandEncoder")}}. Most of these commands originate from the GPURenderPassEncoder created via {{domxref("GPUCommandEncoder.beginRenderPass()")}}. draw() is used to specify that three vertices should be drawn to create our triangle.

// …

const renderPipeline = device.createRenderPipeline(pipelineDescriptor);

// Create GPUCommandEncoder to issue commands to the GPU
// Note: render pass descriptor, command encoder, etc. are destroyed after use, fresh one needed for each frame.
const commandEncoder = device.createCommandEncoder();

// Create GPURenderPassDescriptor to tell WebGPU which texture to draw into, then initiate render pass
const renderPassDescriptor = {
  colorAttachments: [
    {
      clearValue: clearColor,
      loadOp: "clear",
      storeOp: "store",
      view: context.getCurrentTexture().createView(),
    },
  ],
};

const passEncoder = commandEncoder.beginRenderPass(renderPassDescriptor);

// Draw the triangle
passEncoder.setPipeline(renderPipeline);
passEncoder.setVertexBuffer(0, vertexBuffer);
passEncoder.draw(3);

// End the render pass
passEncoder.end();

// End frame by passing array of command buffers to command queue for execution
device.queue.submit([commandEncoder.finish()]);

// …

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also

• The WebGPU API