glTexImage1D(3) specify a one-dimensional texture image

C SPECIFICATION

void glTexImage1D(GLenum target, GLint level, GLint internalFormat, GLsizei width, GLint border, GLenum format, GLenum type, const GLvoid * data);

PARAMETERS

target

Specifies the target texture. Must be GL_TEXTURE_1D or GL_PROXY_TEXTURE_1D.

level

Specifies the level-of-detail number. Level 0 is the base image level. Level n is the nth mipmap reduction image.

internalFormat

Specifies the number of color components in the texture. Must be one of base internal formats given in Table 1, one of the sized internal formats given in Table 2, or one of the compressed internal formats given in Table 3, below.

width

Specifies the width of the texture image. All implementations support texture images that are at least 1024 texels wide. The height of the 1D texture image is 1.

border

This value must be 0.

format

Specifies the format of the pixel data. The following symbolic values are accepted: GL_RED, GL_RG, GL_RGB, GL_BGR, GL_RGBA, and GL_BGRA.

type

Specifies the data type of the pixel data. The following symbolic values are accepted: GL_UNSIGNED_BYTE, GL_BYTE, GL_UNSIGNED_SHORT, GL_SHORT, GL_UNSIGNED_INT, GL_INT, GL_FLOAT, GL_UNSIGNED_BYTE_3_3_2, GL_UNSIGNED_BYTE_2_3_3_REV, GL_UNSIGNED_SHORT_5_6_5, GL_UNSIGNED_SHORT_5_6_5_REV, GL_UNSIGNED_SHORT_4_4_4_4, GL_UNSIGNED_SHORT_4_4_4_4_REV, GL_UNSIGNED_SHORT_5_5_5_1, GL_UNSIGNED_SHORT_1_5_5_5_REV, GL_UNSIGNED_INT_8_8_8_8, GL_UNSIGNED_INT_8_8_8_8_REV, GL_UNSIGNED_INT_10_10_10_2, and GL_UNSIGNED_INT_2_10_10_10_REV.

data

Specifies a pointer to the image data in memory.

DESCRIPTION

Texturing maps a portion of a specified texture image onto each graphical primitive for which texturing is enabled. To enable and disable one-dimensional texturing, call glEnable() and glDisable() with argument GL_TEXTURE_1D.

Texture images are defined with glTexImage1D. The arguments describe the parameters of the texture image, such as width, width of the border, level-of-detail number (see glTexParameter()), and the internal resolution and format used to store the image. The last three arguments describe how the image is represented in memory.

If target is GL_PROXY_TEXTURE_1D, 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_1D, 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 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 left end of the texture array. Subsequent elements progress left-to-right through the remaining texels in the texture array. The final element corresponds to the right end of the texture array.

format determines the composition of each element in data. It can assume one of these symbolic values:

GL_RED

Each element is a single red component. The GL converts it to floating point and assembles it into an RGBA element by attaching 0 for green and blue, and 1 for alpha. Each component is then multiplied by the signed scale factor GL_c_SCALE, added to the signed bias GL_c_BIAS, and clamped to the range [0,1].

GL_RG

Each element is a single red/green double The GL converts it to floating point and assembles it into an RGBA element by attaching 0 for blue, and 1 for alpha. Each component is then multiplied by the signed scale factor GL_c_SCALE, added to the signed bias GL_c_BIAS, and clamped to the range [0,1].

GL_RGB

GL_BGR

Each element is an RGB triple. The GL converts it to floating point and assembles it into an RGBA element by attaching 1 for alpha. Each component is then multiplied by the signed scale factor GL_c_SCALE, added to the signed bias GL_c_BIAS, and clamped to the range [0,1].

GL_RGBA

GL_BGRA

Each element contains all four components. Each component is multiplied by the signed scale factor GL_c_SCALE, added to the signed bias GL_c_BIAS, and clamped to the range [0,1].

GL_DEPTH_COMPONENT

Each element is a single depth value. The GL converts it to floating point, multiplies by the signed scale factor GL_DEPTH_SCALE, adds the signed bias GL_DEPTH_BIAS, and clamps to the range [0,1].

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


Table 1. Base Internal Formats


            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


Table 2. Sized Internal Formats


            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


Table 3. Compressed Internal Formats


            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_ALPHAor 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 ≤ 0.04045 ( c s + 0.055 1.055 ) 2.4 if c s > 0.04045

Assume c s is the sRGB component in the range [0,1].

Use the GL_PROXY_TEXTURE_1D 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 from data. A two-component image uses the R and A 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.

NOTES

glPixelStore() modes affect texture images.

data may be a null pointer. In this case texture memory is allocated to accommodate a texture of width width. You can then download subtextures to initialize the texture memory. The image is undefined if the program tries to apply an uninitialized portion of the texture image to a primitive.

glTexImage1D specifies the one-dimensional texture for the current texture unit, specified with glActiveTexture().

ERRORS

GL_INVALID_ENUM is generated if target is not GL_TEXTURE_1D or GL_PROXY_TEXTURE_1D.

GL_INVALID_ENUM is generated if format is not an accepted format constant. Format constants other than GL_STENCIL_INDEX are accepted.

GL_INVALID_ENUM is generated if type is not a type constant.

GL_INVALID_VALUE is generated if level is less than 0.

GL_INVALID_VALUE may be generated if level is greater than log 2 ⁡ max, where max is the returned value of GL_MAX_TEXTURE_SIZE.

GL_INVALID_VALUE is generated if internalFormat is not one of the accepted resolution and format symbolic constants.

GL_INVALID_VALUE is generated if width is less than 0 or greater than GL_MAX_TEXTURE_SIZE.

GL_INVALID_VALUE is generated if non-power-of-two textures are not supported and the width cannot be represented as 2 n + 2 ⁡ border for some integer value of n.

GL_INVALID_VALUE is generated if border is not 0 or 1.

GL_INVALID_OPERATION is generated if type is one of GL_UNSIGNED_BYTE_3_3_2, GL_UNSIGNED_BYTE_2_3_3_REV, GL_UNSIGNED_SHORT_5_6_5, or GL_UNSIGNED_SHORT_5_6_5_REV and format is not GL_RGB.

GL_INVALID_OPERATION is generated if type is one of GL_UNSIGNED_SHORT_4_4_4_4, GL_UNSIGNED_SHORT_4_4_4_4_REV, GL_UNSIGNED_SHORT_5_5_5_1, GL_UNSIGNED_SHORT_1_5_5_5_REV, GL_UNSIGNED_INT_8_8_8_8, GL_UNSIGNED_INT_8_8_8_8_REV, GL_UNSIGNED_INT_10_10_10_2, or GL_UNSIGNED_INT_2_10_10_10_REV and format is neither GL_RGBA nor GL_BGRA.

GL_INVALID_OPERATION is generated if format is GL_DEPTH_COMPONENT and internalFormat is not GL_DEPTH_COMPONENT, GL_DEPTH_COMPONENT16, GL_DEPTH_COMPONENT24, or GL_DEPTH_COMPONENT32.

GL_INVALID_OPERATION is generated if internalFormat is GL_DEPTH_COMPONENT, GL_DEPTH_COMPONENT16, GL_DEPTH_COMPONENT24, or GL_DEPTH_COMPONENT32, and format is not GL_DEPTH_COMPONENT.

GL_INVALID_OPERATION is generated if a non-zero buffer object name is bound to the GL_PIXEL_UNPACK_BUFFER target and the buffer object's data store is currently mapped.

GL_INVALID_OPERATION is generated if a non-zero buffer object name is bound to the GL_PIXEL_UNPACK_BUFFER target and the data would be unpacked from the buffer object such that the memory reads required would exceed the data store size.

GL_INVALID_OPERATION is generated if a non-zero buffer object name is bound to the GL_PIXEL_UNPACK_BUFFER target and data is not evenly divisible into the number of bytes needed to store in memory a datum indicated by type.

ASSOCIATED GETS

glGetTexImage()

glGet() with argument GL_PIXEL_UNPACK_BUFFER_BINDING

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Copyright © 1991-2006 Silicon Graphics, Inc. Copyright © 2011 Khronos Group. This document is licensed under the SGI Free Software B License. For details, see m[blue]http://oss.sgi.com/projects/FreeB/m[].