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WebGLRenderingContext: compressedTexSubImage2D() method

The WebGLRenderingContext.compressedTexSubImage2D() method of the 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 before using this method or a WebGL2RenderingContext must be used.

Syntax

// 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 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 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 GLint specifying the horizontal offset within the compressed texture image.

yoffset

A GLint specifying the vertical offset within the compressed texture image.

width

A GLsizei specifying the width of the compressed texture.

height

A GLsizei specifying the height of the compressed texture.

format

A GLenum specifying the compressed image format. Compressed image formats must be enabled by WebGL extensions before using this method. Possible values:

When using the 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 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 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 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 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 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 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 GLsizei specifying the number of bytes to read from the buffer bound to gl.PIXEL_UNPACK_BUFFER.

offset

A GLintptr specifying the offset in bytes from which to read from the buffer bound to gl.PIXEL_UNPACK_BUFFER.

srcData

A TypedArray or a DataView that will be used as a data store for the compressed image data in memory.

Return value

None (undefined).

Examples

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

Specification
WebGL Specification # COMPRESSEDTEXSUBIMAGE2D

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