WebGLRenderingContext: viewport() method
Baseline Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
The WebGLRenderingContext.viewport() method of the WebGL API sets the viewport, which specifies
the affine transformation of x and y from normalized device coordinates to window
coordinates.
Syntax
viewport(x, y, width, height)
Parameters
x-
A
GLintspecifying the horizontal coordinate for the lower left corner of the viewport origin. Default value: 0. y-
A
GLintspecifying the vertical coordinate for the lower left corner of the viewport origin. Default value: 0. width-
A non-negative
GLsizeispecifying the width of the viewport. Default value: width of the canvas. height-
A non-negative
GLsizeispecifying the height of the viewport. Default value: height of the canvas.
Return value
None (undefined).
Exceptions
If either width or height is a negative value, a
gl.INVALID_VALUE error is thrown.
Examples
When you first create a WebGL context, the size of the viewport will match the size of
the canvas. However, if you resize the canvas, you will need to tell the WebGL context a
new viewport setting. In this situation, you can use gl.viewport.
gl.viewport(0, 0, canvas.width, canvas.height);
The viewport width and height are clamped to a range that is implementation dependent.
To get this range, you can use the MAX_VIEWPORT_DIMS constant, which
returns an Int32Array.
gl.getParameter(gl.MAX_VIEWPORT_DIMS);
// e.g. Int32Array[16384, 16384]
To get the current viewport, query the VIEWPORT constant.
gl.getParameter(gl.VIEWPORT);
// e.g. Int32Array[0, 0, 640, 480]
Specifications
| Specification |
|---|
| WebGL Specification # 5.14.4 |
Browser compatibility
BCD tables only load in the browser