0,0 → 1,804 |
Name |
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MESA_texture_array |
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Name Strings |
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GL_MESA_texture_array |
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Contact |
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Ian Romanick, IBM (idr 'at' us.ibm.com) |
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IP Status |
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No known IP issues. |
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Status |
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Shipping in Mesa 7.1 |
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Version |
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Number |
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TBD |
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Dependencies |
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OpenGL 1.2 or GL_EXT_texture3D is required. |
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Support for ARB_fragment_program is assumed, but not required. |
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Support for ARB_fragment_program_shadow is assumed, but not required. |
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Support for EXT_framebuffer_object is assumed, but not required. |
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Written based on the wording of the OpenGL 2.0 specification and |
ARB_fragment_program_shadow but not dependent on them. |
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Overview |
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There are a number of circumstances where an application may wish to |
blend two textures out of a larger set of textures. Moreover, in some |
cases the selected textures may vary on a per-fragment basis within |
a polygon. Several examples include: |
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1. High dynamic range textures. The application stores several |
different "exposures" of an image as different textures. On a |
per-fragment basis, the application selects which exposures are |
used. |
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2. A terrain engine where the altitude of a point determines the |
texture applied to it. If the transition is from beach sand to |
grass to rocks to snow, the application will store each texture |
in a different texture map, and dynamically select which two |
textures to blend at run-time. |
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3. Storing short video clips in textures. Each depth slice is a |
single frame of video. |
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Several solutions to this problem have been proposed, but they either |
involve using a separate texture unit for each texture map or using 3D |
textures without mipmaps. Both of these options have major drawbacks. |
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This extension provides a third alternative that eliminates the major |
drawbacks of both previous methods. A new texture target, |
TEXTURE_2D_ARRAY, is added that functions identically to TEXTURE_3D in |
all aspects except the sizes of the non-base level images. In |
traditional 3D texturing, the size of the N+1 LOD is half the size |
of the N LOD in all three dimensions. For the TEXTURE_2D_ARRAY target, |
the height and width of the N+1 LOD is halved, but the depth is the |
same for all levels of detail. The texture then becomes an array of |
2D textures. The per-fragment texel is selected by the R texture |
coordinate. |
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References: |
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http://www.opengl.org/discussion_boards/cgi_directory/ultimatebb.cgi?ubb=get_topic;f=3;t=011557 |
http://www.opengl.org/discussion_boards/cgi_directory/ultimatebb.cgi?ubb=get_topic;f=3;t=000516 |
http://www.opengl.org/discussion_boards/cgi_directory/ultimatebb.cgi?ubb=get_topic;f=3;t=011903 |
http://www.delphi3d.net/articles/viewarticle.php?article=terraintex.htm |
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New Procedures and Functions |
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All functions come directly from EXT_texture_array. |
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void FramebufferTextureLayerEXT(enum target, enum attachment, |
uint texture, int level, int layer); |
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New Tokens |
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All token names and values come directly from EXT_texture_array. |
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Accepted by the <cap> parameter of Enable, Disable, and IsEnabled, by |
the <pname> parameter of GetBooleanv, GetIntegerv, GetFloatv, and |
GetDoublev, and by the <target> parameter of TexImage3D, GetTexImage, |
GetTexLevelParameteriv, GetTexLevelParameterfv, GetTexParameteriv, and |
GetTexParameterfv: |
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TEXTURE_1D_ARRAY_EXT 0x8C18 |
TEXTURE_2D_ARRAY_EXT 0x8C1A |
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Accepted by the <target> parameter of TexImage2D, TexSubImage2D, |
CopyTexImage2D, CopyTexSubImage2D, CompressedTexImage2D, |
CompressedTexSubImage2D, GetTexLevelParameteriv, and |
GetTexLevelParameterfv: |
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TEXTURE_1D_ARRAY_EXT |
PROXY_TEXTURE_1D_ARRAY_EXT 0x8C19 |
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Accepted by the <target> parameter of TexImage3D, TexSubImage3D, |
CopyTexSubImage3D, CompressedTexImage3D, CompressedTexSubImage3D, |
GetTexLevelParameteriv, and GetTexLevelParameterfv: |
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TEXTURE_2D_ARRAY_EXT |
PROXY_TEXTURE_2D_ARRAY_EXT 0x8C1B |
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Accepted by the <pname> parameter of GetBooleanv, GetIntegerv, |
GetFloatv, and GetDoublev |
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TEXTURE_BINDING_1D_ARRAY_EXT 0x8C1C |
TEXTURE_BINDING_2D_ARRAY_EXT 0x8C1D |
MAX_ARRAY_TEXTURE_LAYERS_EXT 0x88FF |
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Accepted by the <param> parameter of TexParameterf, TexParameteri, |
TexParameterfv, and TexParameteriv when the <pname> parameter is |
TEXTURE_COMPARE_MODE_ARB: |
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COMPARE_REF_DEPTH_TO_TEXTURE_EXT 0x884E |
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(Note: COMPARE_REF_DEPTH_TO_TEXTURE_EXT is simply an alias for the |
existing COMPARE_R_TO_TEXTURE token in OpenGL 2.0; the alternate name |
reflects the fact that the R coordinate is not always used.) |
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Accepted by the <internalformat> parameter of TexImage3D and |
CompressedTexImage3D, and by the <format> parameter of |
CompressedTexSubImage3D: |
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COMPRESSED_RGB_S3TC_DXT1_EXT |
COMPRESSED_RGBA_S3TC_DXT1_EXT |
COMPRESSED_RGBA_S3TC_DXT3_EXT |
COMPRESSED_RGBA_S3TC_DXT5_EXT |
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Accepted by the <pname> parameter of |
GetFramebufferAttachmentParameterivEXT: |
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FRAMEBUFFER_ATTACHMENT_TEXTURE_LAYER_EXT 0x8CD4 |
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(Note: FRAMEBUFFER_ATTACHMENT_TEXTURE_LAYER is simply an alias for the |
FRAMEBUFFER_ATTACHMENT_TEXTURE_3D_ZOFFSET_EXT token provided in |
EXT_framebuffer_object. This extension generalizes the notion of |
"<zoffset>" to include layers of an array texture.) |
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Additions to Chapter 2 of the OpenGL 2.0 Specification (OpenGL Operation) |
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None |
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Additions to Chapter 3 of the OpenGL 2.0 Specification (Rasterization) |
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-- Section 3.8.1 "Texture Image Specification" |
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Change the first paragraph (page 150) to say (spec changes identical to |
EXT_texture_array): |
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"The command |
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void TexImage3D(enum target, int level, int internalformat, |
sizei width, sizei height, sizei depth, int border, |
enum format, enum type, void *data); |
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is used to specify a three-dimensional texture image. target must be one |
one of TEXTURE_3D for a three-dimensional texture or |
TEXTURE_2D_ARRAY_EXT for an two-dimensional array texture. |
Additionally, target may be either PROXY_TEXTURE_3D for a |
three-dimensional proxy texture, or PROXY_TEXTURE_2D_ARRAY_EXT for a |
two-dimensional proxy array texture." |
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Change the fourth paragraph on page 151 to say (spec changes identical |
to EXT_texture_array): |
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"Textures with a base internal format of DEPTH_COMPONENT are supported |
by texture image specification commands only if target is TEXTURE_1D, |
TEXTURE_2D, TEXTURE_1D_ARRAY_EXT, TEXTURE_2D_ARRAY_EXT, |
PROXY_TEXTURE_1D, PROXY_TEXTURE_2D, PROXY_TEXTURE_1D_ARRAY_EXT, or |
PROXY_TEXTURE_2D_ARRAY_EXT. Using this format in conjunction with any |
other target will result in an INVALID_OPERATION error." |
|
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Change the fourth paragraph on page 156 to say (spec changes identical |
to EXT_texture_array): |
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"The command |
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void TexImage2D(enum target, int level, |
int internalformat, sizei width, sizei height, |
int border, enum format, enum type, void *data); |
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is used to specify a two-dimensional texture image. target must be one |
of TEXTURE_2D for a two-dimensional texture, TEXTURE_1D_ARRAY_EXT for a |
one-dimensional array texture, or one of TEXTURE_CUBE_MAP_POSITIVE_X, |
TEXTURE_CUBE_MAP_NEGATIVE_X, TEXTURE_CUBE_MAP_POSITIVE_Y, |
TEXTURE_CUBE_MAP_NEGATIVE_Y, TEXTURE_CUBE_MAP_POSITIVE_Z, or |
TEXTURE_CUBE_MAP_NEGATIVE_Z for a cube map texture. Additionally, |
target may be either PROXY_TEXTURE_2D for a two-dimensional proxy |
texture, PROXY_TEXTURE_1D_ARRAY_EXT for a one-dimensional proxy array |
texture, or PROXY TEXTURE_CUBE_MAP for a cube map proxy texture in the |
special case discussed in section 3.8.11. The other parameters match |
the corresponding parameters of TexImage3D. |
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For the purposes of decoding the texture image, TexImage2D is |
equivalent to calling TexImage3D with corresponding arguments and depth |
of 1, except that |
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* The border depth, d_b, is zero, and the depth of the image is |
always 1 regardless of the value of border. |
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* The border height, h_b, is zero if <target> is |
TEXTURE_1D_ARRAY_EXT, and <border> otherwise. |
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* Convolution will be performed on the image (possibly changing its |
width and height) if SEPARABLE 2D or CONVOLUTION 2D is enabled. |
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* UNPACK SKIP IMAGES is ignored." |
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-- Section 3.8.2 "Alternate Texture Image Specification Commands" |
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Change the second paragraph (page 159) (spec changes identical |
to EXT_texture_array): |
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"The command |
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void CopyTexImage2D(enum target, int level, |
enum internalformat, int x, int y, sizei width, |
sizei height, int border); |
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defines a two-dimensional texture image in exactly the manner of |
TexImage2D, except that the image data are taken from the framebuffer |
rather than from client memory. Currently, target must be one of |
TEXTURE_2D, TEXTURE_1D_ARRAY_EXT, TEXTURE_CUBE_MAP_POSITIVE_X, |
TEXTURE_CUBE_MAP_NEGATIVE_X, TEXTURE_CUBE MAP_POSITIVE_Y, |
TEXTURE_CUBE_MAP_NEGATIVE_Y, TEXTURE_CUBE_MAP_POSITIVE_Z, or |
TEXTURE_CUBE_MAP_NEGATIVE_Z. |
|
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Change the last paragraph on page 160 to say (spec changes identical |
to EXT_texture_array): |
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"Currently the target arguments of TexSubImage1D and CopyTexSubImage1D |
must be TEXTURE_1D, the target arguments of TexSubImage2D and |
CopyTexSubImage2D must be one of TEXTURE_2D, TEXTURE_1D_ARRAY_EXT, |
TEXTURE_CUBE_MAP_POSITIVE_X, TEXTURE_CUBE_MAP_NEGATIVE_X, |
TEXTURE_CUBE_MAP_POSITIVE_Y, TEXTURE_CUBE_MAP_NEGATIVE_Y, |
TEXTURE_CUBE_MAP_POSITIVE_Z, or TEXTURE_CUBE_MAP_NEGATIVE_Z, and the |
target arguments of TexSubImage3D and CopyTexSubImage3D must be |
TEXTURE_3D or TEXTURE_2D_ARRAY_EXT. ..." |
|
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-- Section 3.8.4 "Texture Parameters" |
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Change the first paragraph (page 166) to say: |
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"Various parameters control how the texel array is treated when |
specified or changed, and when applied to a fragment. Each parameter is |
set by calling |
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void TexParameter{if}(enum target, enum pname, T param); |
void TexParameter{if}v(enum target, enum pname, T params); |
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target is the target, either TEXTURE_1D, TEXTURE_2D, TEXTURE_3D, |
TEXTURE_CUBE_MAP, TEXTURE_1D_ARRAY_EXT, or TEXTURE_2D_ARRAY_EXT." |
|
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-- Section 3.8.8 "Texture Minification" in the section "Scale Factor and Level of Detail" |
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Change the first paragraph (page 172) to say: |
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"Let s(x,y) be the function that associates an s texture coordinate |
with each set of window coordinates (x,y) that lie within a primitive; |
define t(x,y) and r(x,y) analogously. Let u(x,y) = w_t * s(x,y), |
v(x,y) = h_t * t(x,y), and w(x,y) = d_t * r(x,y), where w_t, h_t, |
and d_t are as defined by equations 3.15, 3.16, and 3.17 with |
w_s, h_s, and d_s equal to the width, height, and depth of the |
image array whose level is level_base. For a one-dimensional |
texture or a one-dimensional array texture, define v(x,y) = 0 and |
w(x,y) = 0; for a two-dimensional texture or a two-dimensional array |
texture, define w(x,y) = 0..." |
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-- Section 3.8.8 "Texture Minification" in the section "Mipmapping" |
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Change the third paragraph (page 174) to say: |
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"For a two-dimensional texture, two-dimensional array texture, or |
cube map texture," |
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Change the fourth paragraph (page 174) to say: |
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"And for a one-dimensional texture or a one-dimensional array texture," |
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After the first paragraph (page 175) add: |
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"For one-dimensional array textures, h_b and d_b are treated as 1, |
regardless of the actual values, when performing mipmap calculations. |
For two-dimensional array textures, d_b is always treated as one, |
regardless of the actual value, when performing mipmap calculations." |
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-- Section 3.8.8 "Automatic Mipmap Generation" in the section "Mipmapping" |
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Change the third paragraph (page 176) to say (spec changes identical |
to EXT_texture_array): |
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"The contents of the derived arrays are computed by repeated, filtered |
reduction of the level_base array. For one- and two-dimensional array |
textures, each layer is filtered independently. ..." |
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-- Section 3.8.8 "Manual Mipmap Generation" in the section "Mipmapping" |
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Change first paragraph to say (spec changes identical to |
EXT_texture_array): |
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"Mipmaps can be generated manually with the command |
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void GenerateMipmapEXT(enum target); |
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where <target> is one of TEXTURE_1D, TEXTURE_2D, TEXTURE_CUBE_MAP, |
TEXTURE_3D, TEXTURE_1D_ARRAY, or TEXTURE_2D_ARRAY. Mipmap generation |
affects the texture image attached to <target>. ..." |
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-- Section 3.8.10 "Texture Completeness" |
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Change the second paragraph (page 177) to say (spec changes identical |
to EXT_texture_array): |
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"For one-, two-, or three-dimensional textures and one- or |
two-dimensional array textures, a texture is complete if the following |
conditions all hold true:" |
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-- Section 3.8.11 "Texture State and Proxy State" |
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Change the second and third paragraphs (page 179) to say (spec changes |
identical to EXT_texture_array): |
|
"In addition to image arrays for one-, two-, and three-dimensional |
textures, one- and two-dimensional array textures, and the six image |
arrays for the cube map texture, partially instantiated image arrays |
are maintained for one-, two-, and three-dimensional textures and one- |
and two-dimensional array textures. Additionally, a single proxy image |
array is maintained for the cube map texture. Each proxy image array |
includes width, height, depth, border width, and internal format state |
values, as well as state for the red, green, blue, alpha, luminance, |
and intensity component resolutions. Proxy image arrays do not include |
image data, nor do they include texture properties. When TexImage3D is |
executed with target specified as PROXY_TEXTURE_3D, the |
three-dimensional proxy state values of the specified level-of-detail |
are recomputed and updated. If the image array would not be supported |
by TexImage3D called with target set to TEXTURE 3D, no error is |
generated, but the proxy width, height, depth, border width, and |
component resolutions are set to zero. If the image array would be |
supported by such a call to TexImage3D, the proxy state values are set |
exactly as though the actual image array were being specified. No pixel |
data are transferred or processed in either case. |
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Proxy arrays for one- and two-dimensional textures and one- and |
two-dimensional array textures are operated on in the same way when |
TexImage1D is executed with target specified as PROXY_TEXTURE_1D, |
TexImage2D is executed with target specified as PROXY_TEXTURE_2D or |
PROXY_TEXTURE_1D_ARRAY_EXT, or TexImage3D is executed with target |
specified as PROXY_TETXURE_2D_ARRAY_EXT." |
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-- Section 3.8.12 "Texture Objects" |
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Change section (page 180) to say (spec changes identical to |
EXT_texture_array): |
|
"In addition to the default textures TEXTURE_1D, TEXTURE_2D, |
TEXTURE_3D, TEXTURE_CUBE_MAP, TEXTURE_1D_ARRAY_EXT, and TEXTURE_2D_EXT, |
named one-, two-, and three-dimensional, cube map, and one- and |
two-dimensional array texture objects can be created and operated upon. |
The name space for texture objects is the unsigned integers, with zero |
reserved by the GL. |
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A texture object is created by binding an unused name to TEXTURE_1D, |
TEXTURE_2D, TEXTURE_3D, TEXTURE_CUBE_MAP, TEXTURE_1D_ARRAY_EXT, or |
TEXTURE_2D_ARRAY_EXT. The binding is effected by calling |
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void BindTexture(enum target, uint texture); |
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with <target> set to the desired texture target and <texture> set to |
the unused name. The resulting texture object is a new state vector, |
comprising all the state values listed in section 3.8.11, set to the |
same initial values. If the new texture object is bound to TEXTURE_1D, |
TEXTURE_2D, TEXTURE_3D, TEXTURE_CUBE_MAP, TEXTURE_1D_ARRAY_EXT, or |
TEXTURE_2D_ARRAY_EXT, it is and remains a one-, two-, |
three-dimensional, cube map, one- or two-dimensional array texture |
respectively until it is deleted. |
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BindTexture may also be used to bind an existing texture object to |
either TEXTURE_1D, TEXTURE_2D, TEXTURE_3D, TEXTURE_CUBE_MAP, |
TEXTURE_1D_ARRAY_EXT, or TEXTURE_2D_ARRAY_EXT. The error |
INVALID_OPERATION is generated if an attempt is made to bind a texture |
object of different dimensionality than the specified target. If the |
bind is successful no change is made to the state of the bound texture |
object, and any previous binding to target is broken. |
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While a texture object is bound, GL operations on the target to which |
it is bound affect the bound object, and queries of the target to which |
it is bound return state from the bound object. If texture mapping of |
the dimensionality of the target to which a texture object is bound is |
enabled, the state of the bound texture object directs the texturing |
operation. |
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In the initial state, TEXTURE_1D, TEXTURE_2D, TEXTURE_3D, |
TEXTURE_CUBE_MAP, TEXTURE_1D_ARRAY_EXT, and TEXTURE_2D_ARRAY_EXT have |
one-, two-, three-dimensional, cube map, and one- and two-dimensional |
array texture state vectors respectively associated with them. In order |
that access to these initial textures not be lost, they are treated as |
texture objects all of whose names are 0. The initial one-, two-, |
three-dimensional, cube map, one- and two-dimensional array textures |
are therefore operated upon, queried, and applied as TEXTURE_1D, |
TEXTURE_2D, TEXTURE_3D, TEXTURE_CUBE_MAP, TEXTURE_1D_ARRAY_EXT, and |
TEXTURE_2D_ARRAY_EXT respectively while 0 is bound to the corresponding |
targets. |
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Change second paragraph on page 181 to say (spec changes identical to |
EXT_texture_array): |
|
"... If a texture that is currently bound to one of the targets |
TEXTURE_1D, TEXTURE_2D, TEXTURE_3D, TEXTURE_CUBE_MAP, |
TEXTURE_1D_ARRAY_EXT, or TEXTURE_2D_ARRAY_EXT is deleted, it is as |
though BindTexture had been executed with the same target and texture |
zero. ..." |
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Change second paragraph on page 182 to say (spec changes identical to |
EXT_texture_array): |
|
"The texture object name space, including the initial one-, two-, and |
three dimensional, cube map, and one- and two-dimensional array texture |
objects, is shared among all texture units. ..." |
|
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-- Section 3.8.14 "Depth Texture Comparison Modes" in "Texture Comparison Modes" |
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Change second through fourth paragraphs (page 188) to say: |
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"Let D_t be the depth texture value, in the range [0, 1]. For |
texture lookups from one- and two-dimensional, rectangle, and |
one-dimensional array targets, let R be the interpolated <r> |
texture coordinate, clamped to the range [0, 1]. For texture lookups |
from two-dimensional array texture targets, let R be the interpolated |
<q> texture coordinate, clamped to the range [0, 1]. Then the |
effective texture value L_t, I_t, or A_t is computed as follows: |
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If the value of TEXTURE_COMPARE_MODE is NONE, then |
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r = Dt |
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If the value of TEXTURE_COMPARE_MODE is |
COMPARE_REF_DEPTH_TO_TEXTURE_EXT), then r depends on the texture |
comparison function as shown in table 3.27." |
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-- Section 3.8.15 "Texture Application" |
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Change the first paragraph (page 189) to say: |
|
"Texturing is enabled or disabled using the generic Enable and Disable |
commands, respectively, with the symbolic constants TEXTURE_1D, |
TEXTURE_2D, TEXTURE_3D, TEXTURE_CUBE_MAP, TEXTURE_1D_ARRAY_EXT, or |
TEXTURE_2D_ARRAY_EXT to enable one-, two-, three-dimensional, cube |
map, one-dimensional array, or two-dimensional array texture, |
respectively. If both two- and one-dimensional textures are enabled, |
the two-dimensional texture is used. If the three-dimensional and |
either of the two- or one-dimensional textures is enabled, the |
three-dimensional texture is used. If the cube map texture and any of |
the three-, two-, or one-dimensional textures is enabled, then cube map |
texturing is used. If one-dimensional array texture is enabled and any |
of cube map, three-, two-, or one-dimensional textures is enabled, |
one-dimensional array texturing is used. If two-dimensional array |
texture is enabled and any of cube map, three-, two-, one-dimensional |
textures or one-dimensional array texture is enabled, two-dimensional |
array texturing is used..." |
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-- Section 3.11.2 of ARB_fragment_program (Fragment Program Grammar and Restrictions): |
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(mostly add to existing grammar rules) |
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<optionName> ::= "MESA_texture_array" |
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<texTarget> ::= "1D" |
| "2D" |
| "3D" |
| "CUBE" |
| "RECT" |
| <arrayTarget> (if program option is present) |
| <shadowTarget> (if program option is present) |
|
<arrayTarget> ::= "ARRAY1D" |
| "ARRAY2D" |
|
<shadowTarget> ::= "SHADOW1D" |
| "SHADOW2D" |
| "SHADOWRECT" |
| <shadowArrayTarget> (if program option is present) |
|
<shadowArrayTarget> ::= "SHADOWARRAY1D" |
| "SHADOWARRAY2D" |
|
|
-- Add Section 3.11.4.5.4 "Texture Stack Option" |
|
"If a fragment program specifies the "MESA_texture_array" program |
option, the <texTarget> rule is modified to add the texture targets |
ARRAY1D and ARRAY2D (See Section 3.11.2)." |
|
-- Section 3.11.6 "Fragment Program Texture Instruction Set" |
|
(replace 1st and 2nd paragraphs with the following paragraphs) |
|
"The first three texture instructions described below specify the |
mapping of 4-tuple input vectors to 4-tuple output vectors. |
The sampling of the texture works as described in section 3.8, |
except that texture environments and texture functions are not |
applicable, and the texture enables hierarchy is replaced by explicit |
references to the desired texture target (i.e., 1D, 2D, 3D, cube map, |
rectangle, ARRAY1D, ARRAY2D). These texture instructions specify |
how the 4-tuple is mapped into the coordinates used for sampling. The |
following function is used to describe the texture sampling in the |
descriptions below: |
|
vec4 TextureSample(vec4 coord, float lodBias, int texImageUnit, |
enum texTarget); |
|
Note that not all four components of the texture coordinates <coord> |
are used by all texture targets. Component usage for each <texTarget> |
is defined in table X. |
|
coordinates used |
texTarget Texture Type s t r layer shadow |
---------------- --------------------- ----- ----- ------ |
1D TEXTURE_1D x - - - - |
2D TEXTURE_2D x y - - - |
3D TEXTURE_3D x y z - - |
CUBE TEXTURE_CUBE_MAP x y z - - |
RECT TEXTURE_RECTANGLE_ARB x y - - - |
ARRAY1D TEXTURE_1D_ARRAY_EXT x - - y - |
ARRAY2D TEXTURE_2D_ARRAY_EXT x y - z - |
SHADOW1D TEXTURE_1D x - - - z |
SHADOW2D TEXTURE_2D x y - - z |
SHADOWRECT TEXTURE_RECTANGLE_ARB x y - - z |
SHADOWARRAY1D TEXTURE_1D_ARRAY_EXT x - - y z |
SHADOWARRAY2D TEXTURE_2D_ARRAY_EXT x y - z w |
|
Table X: Texture types accessed for each of the <texTarget>, and |
coordinate mappings. The "coordinates used" column indicate the |
input values used for each coordinate of the texture lookup, the |
layer selector for array textures, and the reference value for |
texture comparisons." |
|
-- Section 3.11.6.2 "TXP: Project coordinate and map to color" |
|
Add to the end of the section: |
|
"A program will fail to load if the TXP instruction is used in |
conjunction with the SHADOWARRAY2D target." |
|
Additions to Chapter 4 of the OpenGL 2.0 Specification (Per-Fragment Operations) |
|
-- Section 4.4.2.3 "Attaching Texture Images to a Framebuffer" |
|
Add to the end of the section (spec changes identical to |
EXT_texture_array): |
|
"The command |
|
void FramebufferTextureLayerEXT(enum target, enum attachment, |
uint texture, int level, int layer); |
|
operates identically to FramebufferTexture3DEXT, except that it |
attaches a single layer of a three-dimensional texture or a one- or |
two-dimensional array texture. <layer> is an integer indicating the |
layer number, and is treated identically to the <zoffset> parameter in |
FramebufferTexture3DEXT. The error INVALID_VALUE is generated if |
<layer> is negative. The error INVALID_OPERATION is generated if |
<texture> is non-zero and is not the name of a three dimensional |
texture or one- or two-dimensional array texture. Unlike |
FramebufferTexture3D, no <textarget> parameter is accepted. |
|
If <texture> is non-zero and the command does not result in an error, |
the framebuffer attachment state corresponding to <attachment> is |
updated as in the other FramebufferTexture commands, except that |
FRAMEBUFFER_ATTACHMENT_TEXTURE_LAYER_EXT is set to <layer>." |
|
-- Section 4.4.4.1 "Framebuffer Attachment Completeness" |
|
Add to the end of the list of completeness rules (spec changes |
identical to EXT_texture_array): |
|
"* If FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE_EXT is TEXTURE and |
FRAMEBUFFER_ATTACHMENT_OBJECT_NAME_EXT names a one- or |
two-dimensional array texture, then |
FRAMEBUFFER_ATTACHMENT_TEXTURE_LAYER_EXT must be smaller than the |
number of layers in the texture." |
|
Additions to Chapter 5 of the OpenGL 2.0 Specification (Special Functions) |
|
-- Section 5.4 "Display Lists" |
|
Change the first paragraph on page 242 to say (spec changes |
identical to EXT_texture_array): |
|
"TexImage3D, TexImage2D, TexImage1D, Histogram, and ColorTable are |
executed immediately when called with the corresponding proxy arguments |
PROXY_TEXTURE_3D or PROXY_TEXTURE_2D_ARRAY_EXT; PROXY_TEXTURE_2D, |
PROXY_TEXTURE_CUBE_MAP, or PROXY_TEXTURE_1D_ARRAY_EXT; |
PROXY_TEXTURE_1D; PROXY_HISTOGRAM; and PROXY_COLOR_TABLE, |
PROXY_POST_CONVOLUTION_COLOR_TABLE, or |
PROXY_POST_COLOR_MATRIX_COLOR_TABLE." |
|
Additions to Chapter 6 of the OpenGL 2.0 Specification (State and State Requests) |
|
-- Section 6.1.3 "Enumerated Queries" |
|
Add after the line beginning "If the value of |
FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE_EXT is TEXTURE" (spec changes |
identical to EXT_texture_array): |
|
"If <pname> is FRAMEBUFFER_ATTACHMENT_TEXTURE_LAYER_EXT and the |
texture object named FRAMEBUFFER_ATTACHMENT_OBJECT_NAME_EXT is a |
three-dimensional texture or a one- or two-dimensional array texture, |
then <params> will contain the number of texture layer attached to the |
attachment point. Otherwise, <params> will contain the value zero." |
|
-- Section 6.1.4 "Texture Queries" |
|
Change the first three paragraphs (page 248) to say (spec changes |
identical to EXT_texture_array): |
|
"The command |
|
void GetTexImage(enum tex, int lod, enum format, |
enum type, void *img); |
|
is used to obtain texture images. It is somewhat different from the |
other get commands; tex is a symbolic value indicating which texture |
(or texture face in the case of a cube map texture target name) is to |
be obtained. TEXTURE_1D, TEXTURE_2D, TEXTURE_3D, TEXTURE_1D_ARRAY_EXT, |
and TEXTURE_2D_ARRAY_EXT indicate a one-, two-, or three-dimensional |
texture, or one- or two-dimensional array texture, respectively. |
TEXTURE_CUBE_MAP_POSITIVE_X, ... |
|
GetTexImage obtains... from the first image to the last for |
three-dimensional textures. One- and two-dimensional array textures |
are treated as two- and three-dimensional images, respectively, where |
the layers are treated as rows or images. These groups are then... |
|
For three-dimensional and two-dimensional array textures, pixel storage |
operations are applied as if the image were two-dimensional, except |
that the additional pixel storage state values PACK_IMAGE_HEIGHT and |
PACK_SKIP_IMAGES are applied. ..." |
|
Additions to Appendix A of the OpenGL 2.0 Specification (Invariance) |
|
None |
|
Additions to the AGL/GLX/WGL Specifications |
|
None |
|
GLX Protocol |
|
None |
|
Dependencies on ARB_fragment_program |
|
If ARB_fragment_program is not supported, the changes to section 3.11 |
should be ignored. |
|
Dependencies on EXT_framebuffer_object |
|
If EXT_framebuffer_object is not supported, the changes to section |
3.8.8 ("Manual Mipmap Generation"), 4.4.2.3, and 6.1.3 should be ignored. |
|
Dependencies on EXT_texture_compression_s3tc and NV_texture_compression_vtc |
|
(Identical dependency as EXT_texture_array.) |
|
S3TC texture compression is supported for two-dimensional array textures. |
When <target> is TEXTURE_2D_ARRAY_EXT, each layer is stored independently |
as a compressed two-dimensional textures. When specifying or querying |
compressed images using one of the S3TC formats, the images are provided |
and/or returned as a series of two-dimensional textures stored |
consecutively in memory, with the layer closest to zero specified first. |
For array textures, images are not arranged in 4x4x4 or 4x4x2 blocks as in |
the three-dimensional compression format provided in the |
EXT_texture_compression_vtc extension. Pixel store parameters, including |
those specific to three-dimensional images, are ignored when compressed |
image data are provided or returned, as in the |
EXT_texture_compression_s3tc extension. |
|
S3TC compression is not supported for one-dimensional texture targets in |
EXT_texture_compression_s3tc, and is not supported for one-dimensional |
array textures in this extension. If compressed one-dimensional arrays |
are needed, use a two-dimensional texture with a height of one. |
|
This extension allows the use of the four S3TC internal format types in |
TexImage3D, CompressedTexImage3D, and CompressedTexSubImage3D calls. |
|
Errors |
|
None |
|
New State |
|
(add to table 6.15, p. 276) |
|
Initial |
Get Value Type Get Command Value Description Sec. Attribute |
---------------------------- ----- ----------- ----- -------------------- ------ --------- |
TEXTURE_BINDING_1D_ARRAY_EXT 2*xZ+ GetIntegerv 0 texture object bound 3.8.12 texture |
to TEXTURE_1D_ARRAY |
TEXTURE_BINDING_2D_ARRAY_EXT 2*xZ+ GetIntegerv 0 texture object bound 3.8.12 texture |
to TEXTURE_2D_ARRAY |
|
|
New Implementation Dependent State |
|
(add to Table 6.32, p. 293) |
|
Minimum |
Get Value Type Get Command Value Description Sec. Attribute |
---------------------------- ---- ----------- ------- ------------------ ----- --------- |
MAX_TEXTURE_ARRAY_LAYERS_EXT Z+ GetIntegerv 64 maximum number of 3.8.1 - |
layers for texture |
arrays |
|
Issues |
|
(1) Is "texture stack" a good name for this functionality? |
|
NO. The name is changed to "array texture" to match the |
nomenclature used by GL_EXT_texture_array. |
|
(2) Should the R texture coordinate be treated as normalized or |
un-normalized? If it were un-normalized, floor(R) could be thought |
of as a direct index into the array texture. This may be more |
convenient for applications. |
|
RESOLVED. All texture coordinates are normalized. The issue of |
un-normalized texture coordinates has been discussed in the ARB |
before and should be left for a layered extension. |
|
RE-RESOLVED. The R coordinate is un-normalized. Accessing an array |
using [0, layers-1] coordinates is much more natural. |
|
(3) How does LOD selection work for stacked textures? |
|
RESOLVED. For 2D array textures the R coordinate is ignored, and |
the LOD selection equations for 2D textures are used. For 1D |
array textures the T coordinate is ignored, and the LOD selection |
equations for 1D textures are used. The expected usage is in a |
fragment program with an explicit LOD selection. |
|
(4) What is the maximum size of a 2D array texture? Is it the same |
as for a 3D texture, or should a new query be added? How about for 1D |
array textures? |
|
RESOLVED. A new query is added. |
|
(5) How are array textures exposed in GLSL? |
|
RESOLVED. Use GL_EXT_texture_array. |
|
(6) Should a 1D array texture also be exposed? |
|
RESOLVED. For orthogonality, yes. |
|
(7) How are stacked textures attached to framebuffer objects? |
|
RESOLVED. Layers of both one- and two-dimensional array textures |
are attached using FreambufferTextureLayerEXT. Once attached, the |
array texture layer behaves exactly as either a one- or |
two-dimensional texture. |
|
(8) How is this extension related to GL_EXT_texture_array? |
|
This extension adapats GL_MESAX_texture_stack to the notation, |
indexing, and FBO access of GL_EXT_texture_array. This extension |
replaces the GLSL support of GL_EXT_texture_array with |
GL_ARB_fragment_program support. |
|
Assembly program support is also provided by GL_NV_gpu_program4. |
GL_NV_gpu_program4 also adds support for other features that are |
specific to Nvidia hardware, while this extension adds only support |
for array textures. |
|
Much of text of this extension that has changed since |
GL_MESAX_texture_stack comes directly from either |
GL_EXT_texture_array or GL_NV_gpu_program4. |
|
Revision History |
|
||2005/11/15||0.1||idr||Initial draft MESAX version.|| |
||2005/12/07||0.2||idr||Added framebuffer object interactions.|| |
||2005/12/12||0.3||idr||Updated fragment program interactions.|| |
||2007/05/16||0.4||idr||Converted to MESA_texture_array. Brought in line with EXT_texture_array and NV_gpu_program4.|| |