glTexImage2D

glTexImage2D: man4/glTexImage2D.xml

Texturing allows elements of an image array to be read by shaders. To define texture images, call glTexImage2D. The arguments describe the parameters of the texture image, such as height, width, width of the border, level-of-detail number (see glTexParameter ), and number of color components provided. The last three arguments describe how the image is represented in memory. If target is GL_PROXY_TEXTURE_2D, GL_PROXY_TEXTURE_1D_ARRAY, GL_PROXY_TEXTURE_CUBE_MAP, or GL_PROXY_TEXTURE_RECTANGLE, no data is read from data, but all of the texture image state is recalculated, checked for consistency, and checked against the implementation's capabilities. If the implementation cannot handle a texture of the requested texture size, it sets all of the image state to 0, but does not generate an error (see glGetError ). To query for an entire mipmap array, use an image array level greater than or equal to 1. If target is GL_TEXTURE_2D, GL_TEXTURE_RECTANGLE or one of the GL_TEXTURE_CUBE_MAP targets, data is read from data as a sequence of signed or unsigned bytes, shorts, or longs, or single-precision floating-point values, depending on type. These values are grouped into sets of one, two, three, or four values, depending on format, to form elements. Each data byte is treated as eight 1-bit elements, with bit ordering determined by GL_UNPACK_LSB_FIRST (see glPixelStore ). If target is GL_TEXTURE_1D_ARRAY, data is interpreted as an array of one-dimensional images. If a non-zero named buffer object is bound to the GL_PIXEL_UNPACK_BUFFER target (see glBindBuffer ) while a texture image is specified, data is treated as a byte offset into the buffer object's data store. The first element corresponds to the lower left corner of the texture image. Subsequent elements progress left-to-right through the remaining texels in the lowest row of the texture image, and then in successively higher rows of the texture image. The final element corresponds to the upper right corner of the texture image. format determines the composition of each element in data. It can assume one of these symbolic values: If an application wants to store the texture at a certain resolution or in a certain format, it can request the resolution and format with internalFormat. The GL will choose an internal representation that closely approximates that requested by internalFormat, but it may not match exactly. (The representations specified by GL_RED, GL_RG, GL_RGB, and GL_RGBA must match exactly.) internalFormat may be one of the base internal formats shown in Table 1, below<h3> Base Internal Formats</h3> Base Internal Format RGBA, Depth and Stencil Values Internal Components GL_DEPTH_COMPONENT Depth D GL_DEPTH_STENCIL Depth, Stencil D, S GL_RED Red R GL_RG Red, Green R, G GL_RGB Red, Green, Blue R, G, B GL_RGBA Red, Green, Blue, Alpha R, G, B, A internalFormat may also be one of the sized internal formats shown in Table 2, below<h3> Sized Internal Formats</h3> Sized Internal Format Base Internal Format Red Bits Green Bits Blue Bits Alpha Bits Shared Bits GL_R8 GL_RED 8 GL_R8_SNORM GL_RED s8 GL_R16 GL_RED 16 GL_R16_SNORM GL_RED s16 GL_RG8 GL_RG 8 8 GL_RG8_SNORM GL_RG s8 s8 GL_RG16 GL_RG 16 16 GL_RG16_SNORM GL_RG s16 s16 GL_R3_G3_B2 GL_RGB 3 3 2 GL_RGB4 GL_RGB 4 4 4 GL_RGB5 GL_RGB 5 5 5 GL_RGB8 GL_RGB 8 8 8 GL_RGB8_SNORM GL_RGB s8 s8 s8 GL_RGB10 GL_RGB 10 10 10 GL_RGB12 GL_RGB 12 12 12 GL_RGB16_SNORM GL_RGB 16 16 16 GL_RGBA2 GL_RGB 2 2 2 2 GL_RGBA4 GL_RGB 4 4 4 4 GL_RGB5_A1 GL_RGBA 5 5 5 1 GL_RGBA8 GL_RGBA 8 8 8 8 GL_RGBA8_SNORM GL_RGBA s8 s8 s8 s8 GL_RGB10_A2 GL_RGBA 10 10 10 2 GL_RGB10_A2UI GL_RGBA ui10 ui10 ui10 ui2 GL_RGBA12 GL_RGBA 12 12 12 12 GL_RGBA16 GL_RGBA 16 16 16 16 GL_SRGB8 GL_RGB 8 8 8 GL_SRGB8_ALPHA8 GL_RGBA 8 8 8 8 GL_R16F GL_RED f16 GL_RG16F GL_RG f16 f16 GL_RGB16F GL_RGB f16 f16 f16 GL_RGBA16F GL_RGBA f16 f16 f16 f16 GL_R32F GL_RED f32 GL_RG32F GL_RG f32 f32 GL_RGB32F GL_RGB f32 f32 f32 GL_RGBA32F GL_RGBA f32 f32 f32 f32 GL_R11F_G11F_B10F GL_RGB f11 f11 f10 GL_RGB9_E5 GL_RGB 9 9 9 5 GL_R8I GL_RED i8 GL_R8UI GL_RED ui8 GL_R16I GL_RED i16 GL_R16UI GL_RED ui16 GL_R32I GL_RED i32 GL_R32UI GL_RED ui32 GL_RG8I GL_RG i8 i8 GL_RG8UI GL_RG ui8 ui8 GL_RG16I GL_RG i16 i16 GL_RG16UI GL_RG ui16 ui16 GL_RG32I GL_RG i32 i32 GL_RG32UI GL_RG ui32 ui32 GL_RGB8I GL_RGB i8 i8 i8 GL_RGB8UI GL_RGB ui8 ui8 ui8 GL_RGB16I GL_RGB i16 i16 i16 GL_RGB16UI GL_RGB ui16 ui16 ui16 GL_RGB32I GL_RGB i32 i32 i32 GL_RGB32UI GL_RGB ui32 ui32 ui32 GL_RGBA8I GL_RGBA i8 i8 i8 i8 GL_RGBA8UI GL_RGBA ui8 ui8 ui8 ui8 GL_RGBA16I GL_RGBA i16 i16 i16 i16 GL_RGBA16UI GL_RGBA ui16 ui16 ui16 ui16 GL_RGBA32I GL_RGBA i32 i32 i32 i32 GL_RGBA32UI GL_RGBA ui32 ui32 ui32 ui32 Finally, internalFormat may also be one of the generic or compressed compressed texture formats shown in Table 3 below<h3> Compressed Internal Formats</h3> Compressed Internal Format Base Internal Format Type GL_COMPRESSED_RED GL_RED Generic GL_COMPRESSED_RG GL_RG Generic GL_COMPRESSED_RGB GL_RGB Generic GL_COMPRESSED_RGBA GL_RGBA Generic GL_COMPRESSED_SRGB GL_RGB Generic GL_COMPRESSED_SRGB_ALPHA GL_RGBA Generic GL_COMPRESSED_RED_RGTC1 GL_RED Specific GL_COMPRESSED_SIGNED_RED_RGTC1 GL_RED Specific GL_COMPRESSED_RG_RGTC2 GL_RG Specific GL_COMPRESSED_SIGNED_RG_RGTC2 GL_RG Specific GL_COMPRESSED_RGBA_BPTC_UNORM GL_RGBA Specific GL_COMPRESSED_SRGB_ALPHA_BPTC_UNORM GL_RGBA Specific GL_COMPRESSED_RGB_BPTC_SIGNED_FLOAT GL_RGB Specific GL_COMPRESSED_RGB_BPTC_UNSIGNED_FLOAT GL_RGB Specific If the internalFormat parameter is one of the generic compressed formats, GL_COMPRESSED_RED, GL_COMPRESSED_RG, GL_COMPRESSED_RGB, or GL_COMPRESSED_RGBA, the GL will replace the internal format with the symbolic constant for a specific internal format and compress the texture before storage. If no corresponding internal format is available, or the GL can not compress that image for any reason, the internal format is instead replaced with a corresponding base internal format. If the internalFormat parameter is GL_SRGB, GL_SRGB8, GL_SRGB_ALPHA, or GL_SRGB8_ALPHA8, the texture is treated as if the red, green, or blue components are encoded in the sRGB color space. Any alpha component is left unchanged. The conversion from the sRGB encoded component c s to a linear component c l is: c l = { c s 12.92 if c s &le; 0.04045 ( c s + 0.055 1.055 ) 2.4 if c s &gt; 0.04045 Assume c s is the sRGB component in the range [0,1]. Use the GL_PROXY_TEXTURE_2D, GL_PROXY_TEXTURE_1D_ARRAY, GL_PROXY_TEXTURE_RECTANGLE, or GL_PROXY_TEXTURE_CUBE_MAP target to try out a resolution and format. The implementation will update and recompute its best match for the requested storage resolution and format. To then query this state, call glGetTexLevelParameter. If the texture cannot be accommodated, texture state is set to 0. A one-component texture image uses only the red component of the RGBA color extracted from data. A two-component image uses the R and G values. A three-component image uses the R, G, and B values. A four-component image uses all of the RGBA components. Image-based shadowing can be enabled by comparing texture r coordinates to depth texture values to generate a boolean result. See glTexParameter for details on texture comparison.

The glPixelStore mode affects texture images. data may be a null pointer. In this case, texture memory is allocated to accommodate a texture of width width and height height. You can then download subtextures to initialize this texture memory. The image is undefined if the user tries to apply an uninitialized portion of the texture image to a primitive. glTexImage2D specifies the two-dimensional texture for the current texture unit, specified with glActiveTexture. GL_STENCIL_INDEX may be used for format only if the GL version is 4.4 or higher.