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---
title: "WebGLRenderingContext: compressedTexSubImage2D() method"
short-title: compressedTexSubImage2D()
slug: Web/API/WebGLRenderingContext/compressedTexSubImage2D
page-type: web-api-instance-method
browser-compat: api.WebGLRenderingContext.compressedTexSubImage2D
---
{{APIRef("WebGL")}}
The **`WebGLRenderingContext.compressedTexSubImage2D()`**
method of the [WebGL API](/en-US/docs/Web/API/WebGL_API) specifies a
two-dimensional sub-rectangle for a texture image in a compressed format.
Compressed image formats must be enabled by [WebGL extensions](/en-US/docs/Web/API/WebGL_API/Using_Extensions) before
using this method or a {{domxref("WebGL2RenderingContext")}} must be used.
## Syntax
```js-nolint
// WebGL 1:
compressedTexSubImage2D(target, level, xoffset, yoffset, width, height, format, srcData)
// Additionally available in WebGL 2:
compressedTexSubImage2D(target, level, xoffset, yoffset, width, height, format, imageSize, offset)
compressedTexSubImage2D(target, level, xoffset, yoffset, width, height, format, srcData)
compressedTexSubImage2D(target, level, xoffset, yoffset, width, height, format, srcData, srcOffset)
compressedTexSubImage2D(target, level, xoffset, yoffset, width, height, format, srcData, srcOffset, srcLengthOverride)
```
### Parameters
- `target`
- : A {{domxref("WebGL_API/Types", "GLenum")}} specifying the binding point (target) of the active
compressed texture. Possible values:
- `gl.TEXTURE_2D`: A two-dimensional texture.
- `gl.TEXTURE_CUBE_MAP_POSITIVE_X`: Positive X face for a cube-mapped
texture.
- `gl.TEXTURE_CUBE_MAP_NEGATIVE_X`: Negative X face for a cube-mapped
texture.
- `gl.TEXTURE_CUBE_MAP_POSITIVE_Y`: Positive Y face for a cube-mapped
texture.
- `gl.TEXTURE_CUBE_MAP_NEGATIVE_Y`: Negative Y face for a cube-mapped
texture.
- `gl.TEXTURE_CUBE_MAP_POSITIVE_Z`: Positive Z face for a cube-mapped
texture.
- `gl.TEXTURE_CUBE_MAP_NEGATIVE_Z`: Negative Z face for a cube-mapped
texture.
- `level`
- : A {{domxref("WebGL_API/Types", "GLint")}} specifying the level of detail. Level 0 is the base image
level and level _n_ is the n-th mipmap reduction level.
- `xoffset`
- : A {{domxref("WebGL_API/Types", "GLint")}} specifying the horizontal offset within the compressed
texture image.
- `yoffset`
- : A {{domxref("WebGL_API/Types", "GLint")}} specifying the vertical offset within the compressed texture
image.
- `width`
- : A {{domxref("WebGL_API/Types", "GLsizei")}} specifying the width of the compressed texture.
- `height`
- : A {{domxref("WebGL_API/Types", "GLsizei")}} specifying the height of the compressed texture.
- `format`
- : A {{domxref("WebGL_API/Types", "GLenum")}} specifying the compressed image format. Compressed image
formats must be enabled by [WebGL extensions](/en-US/docs/Web/API/WebGL_API/Using_Extensions) before
using this method. Possible values:
- When using the {{domxref("WEBGL_compressed_texture_s3tc")}} extension:
- `ext.COMPRESSED_RGB_S3TC_DXT1_EXT`
- `ext.COMPRESSED_RGBA_S3TC_DXT1_EXT`
- `ext.COMPRESSED_RGBA_S3TC_DXT3_EXT`
- `ext.COMPRESSED_RGBA_S3TC_DXT5_EXT`
- When using the {{domxref("WEBGL_compressed_texture_s3tc_srgb")}} extension:
- `ext.COMPRESSED_SRGB_S3TC_DXT1_EXT`
- `ext.COMPRESSED_SRGB_ALPHA_S3TC_DXT1_EXT`
- `ext.COMPRESSED_SRGB_ALPHA_S3TC_DXT3_EXT`
- `ext.COMPRESSED_SRGB_ALPHA_S3TC_DXT5_EXT`
- When using the {{domxref("WEBGL_compressed_texture_etc")}} extension:
- `ext.COMPRESSED_R11_EAC`
- `ext.COMPRESSED_SIGNED_R11_EAC`
- `ext.COMPRESSED_RG11_EAC`
- `ext.COMPRESSED_SIGNED_RG11_EAC`
- `ext.COMPRESSED_RGB8_ETC2`
- `ext.COMPRESSED_RGBA8_ETC2_EAC`
- `ext.COMPRESSED_SRGB8_ETC2`
- `ext.COMPRESSED_SRGB8_ALPHA8_ETC2_EAC`
- `ext.COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2`
- `ext.COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_ETC2`
- When using the {{domxref("WEBGL_compressed_texture_pvrtc")}} extension:
- `ext.COMPRESSED_RGB_PVRTC_4BPPV1_IMG`
- `ext.COMPRESSED_RGBA_PVRTC_4BPPV1_IMG`
- `ext.COMPRESSED_RGB_PVRTC_2BPPV1_IMG`
- `ext.COMPRESSED_RGBA_PVRTC_2BPPV1_IMG`
- When using the {{domxref("WEBGL_compressed_texture_astc")}} extension:
- `ext.COMPRESSED_RGBA_ASTC_4x4_KHR ext.COMPRESSED_SRGB8_ALPHA8_ASTC_4x4_KHR`
- `ext.COMPRESSED_RGBA_ASTC_5x4_KHR ext.COMPRESSED_SRGB8_ALPHA8_ASTC_5x4_KHR`
- `ext.COMPRESSED_RGBA_ASTC_5x5_KHR ext.COMPRESSED_SRGB8_ALPHA8_ASTC_5x5_KHR`
- `ext.COMPRESSED_RGBA_ASTC_6x5_KHR ext.COMPRESSED_SRGB8_ALPHA8_ASTC_6x5_KHR`
- `ext.COMPRESSED_RGBA_ASTC_6x6_KHR ext.COMPRESSED_SRGB8_ALPHA8_ASTC_6x6_KHR`
- `ext.COMPRESSED_RGBA_ASTC_8x5_KHR ext.COMPRESSED_SRGB8_ALPHA8_ASTC_8x5_KHR`
- `ext.COMPRESSED_RGBA_ASTC_8x6_KHR ext.COMPRESSED_SRGB8_ALPHA8_ASTC_8x6_KHR`
- `ext.COMPRESSED_RGBA_ASTC_8x8_KHR ext.COMPRESSED_SRGB8_ALPHA8_ASTC_8x8_KHR`
- `ext.COMPRESSED_RGBA_ASTC_10x5_KHR ext.COMPRESSED_SRGB8_ALPHA8_ASTC_10x5_KHR`
- `ext.COMPRESSED_RGBA_ASTC_10x6_KHR ext.COMPRESSED_SRGB8_ALPHA8_ASTC_10x6_KHR`
- `ext.COMPRESSED_RGBA_ASTC_10x6_KHR ext.COMPRESSED_SRGB8_ALPHA8_ASTC_10x6_KHR`
- `ext.COMPRESSED_RGBA_ASTC_10x10_KHR ext.COMPRESSED_SRGB8_ALPHA8_ASTC_10x10_KHR`
- `ext.COMPRESSED_RGBA_ASTC_12x10_KHR ext.COMPRESSED_SRGB8_ALPHA8_ASTC_12x10_KHR`
- `ext.COMPRESSED_RGBA_ASTC_12x12_KHR ext.COMPRESSED_SRGB8_ALPHA8_ASTC_12x12_KHR`
- When using the {{domxref("EXT_texture_compression_bptc")}} extension:
- `ext.COMPRESSED_RGBA_BPTC_UNORM_EXT`
- `ext.COMPRESSED_SRGB_ALPHA_BPTC_UNORM_EXT`
- `ext.COMPRESSED_RGB_BPTC_SIGNED_FLOAT_EXT`
- `ext.COMPRESSED_RGB_BPTC_UNSIGNED_FLOAT_EXT`
- When using the {{domxref("EXT_texture_compression_rgtc")}} extension:
- `ext.COMPRESSED_RED_RGTC1_EXT`
- `ext.COMPRESSED_SIGNED_RED_RGTC1_EXT`
- `ext.COMPRESSED_RED_GREEN_RGTC2_EXT`
- `ext.COMPRESSED_SIGNED_RED_GREEN_RGTC2_EXT`
- `imageSize`
- : A {{domxref("WebGL_API/Types", "GLsizei")}} specifying the number of bytes to read from the buffer
bound to `gl.PIXEL_UNPACK_BUFFER`.
- `offset`
- : A {{domxref("WebGL_API/Types", "GLintptr")}} specifying the offset in bytes from which to read from the
buffer bound to `gl.PIXEL_UNPACK_BUFFER`.
- `srcData`
- : A {{jsxref("TypedArray")}} or a {{jsxref("DataView")}} that will be used as a data store for the compressed
image data in memory.
### Return value
None ({{jsxref("undefined")}}).
## Examples
```js
const ext =
gl.getExtension("WEBGL_compressed_texture_s3tc") ||
gl.getExtension("MOZ_WEBGL_compressed_texture_s3tc") ||
gl.getExtension("WEBKIT_WEBGL_compressed_texture_s3tc");
gl.compressedTexSubImage2D(
gl.TEXTURE_2D,
0,
256,
256,
512,
512,
ext.COMPRESSED_RGBA_S3TC_DXT5_EXT,
textureData,
);
```
## Specifications
{{Specifications}}
## Browser compatibility
{{Compat}}
## See also
- [Using WebGL extensions](/en-US/docs/Web/API/WebGL_API/Using_Extensions)
- {{domxref("WebGLRenderingContext.getExtension()")}}
- {{domxref("WebGLRenderingContext.compressedTexImage2D()")}}
- {{domxref("WEBGL_compressed_texture_s3tc")}}
- {{domxref("WEBGL_compressed_texture_s3tc_srgb")}}
- {{domxref("WEBGL_compressed_texture_etc")}}
- {{domxref("WEBGL_compressed_texture_pvrtc")}}
- {{domxref("WEBGL_compressed_texture_astc")}}
- {{domxref("EXT_texture_compression_bptc")}}
- {{domxref("EXT_texture_compression_rgtc")}}