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Text File | 1996-11-11 | 27.4 KB | 669 lines

Name EXT_histogram Name Strings GL_EXT_histogram Version $Date: 1995/09/30 02:31:10 $ $Revision: 1.1 $ Number 11 Dependencies EXT_abgr affects the definition of this extension EXT_texture is required Overview This extension defines pixel operations that count occurences of specific color component values (histogram) and that track the minimum and maximum color component values (minmax). An optional mode allows pixel data to be discarded after the histogram and/or minmax operations are completed. Otherwise the pixel data continue on to the next operation unaffected. New Procedures and Functions void HistogramEXT(enum target, sizei width, enum internalformat, boolean sink); void ResetHistogramEXT(enum target); void GetHistogramEXT(enum target, boolean reset, enum format, enum type, void* values); void GetHistogramParameterivEXT(enum target, enum pname, int* params); void GetHistogramParameterfvEXT(enum target, enum pname, float* params); void MinmaxEXT(enum target, enum internalformat, boolean sink); void ResetMinmaxEXT(enum target); void GetMinmaxEXT(enum target, boolean reset, enum format, enum type, void* values); void GetMinmaxParameterivEXT(enum target, enum pname, int* params); void GetMinmaxParameterfvEXT(enum target, enum pname, float* params); New Tokens 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 HistogramEXT, ResetHistogramEXT, GetHistogramEXT, GetHistogramParameterivEXT, and GetHistogramParameterfvEXT: HISTOGRAM_EXT 0x8024 Accepted by the <target> parameter of HistogramEXT, GetHistogramParameterivEXT, and GetHistogramParameterfvEXT: PROXY_HISTOGRAM_EXT 0x8025 Accepted by the <pname> parameter of GetHistogramParameterivEXT and GetHistogramParameterfvEXT: HISTOGRAM_WIDTH_EXT 0x8026 HISTOGRAM_FORMAT_EXT 0x8027 HISTOGRAM_RED_SIZE_EXT 0x8028 HISTOGRAM_GREEN_SIZE_EXT 0x8029 HISTOGRAM_BLUE_SIZE_EXT 0x802A HISTOGRAM_ALPHA_SIZE_EXT 0x802B HISTOGRAM_LUMINANCE_SIZE_EXT 0x802C HISTOGRAM_SINK_EXT 0x802D 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 MinmaxEXT, ResetMinmaxEXT, and GetMinmaxEXT: MINMAX_EXT 0x802E Accepted by the <pname> parameter of GetMinmaxParameterivEXT and GetMinmaxParameterfvEXT: MINMAX_FORMAT_EXT 0x802F MINMAX_SINK_EXT 0x8030 Additions to Chapter 2 of the 1.0 Specification (OpenGL Operation) A new error token value, TABLE_TOO_LARGE_EXT, is defined and added to table 2.3: Offending command Error Description ignored? ----- ----------- --------- INVALID_ENUM enum argument out of range Yes INVALID_VALUE Numeric argument out of range Yes INVALID_OPERATION Operation illegal in current state Yes STACK_OVERFLOW Command would cause a stack overflow Yes STACK_UNDERFLOW Command would cause a stack underflow Yes OUT_OF_MEMORY Not enough memory left to execute command Unknown TEXTURE_TOO_LARGE_SGI The specified texture is too large Yes TABLE_TOO_LARGE_EXT The specified table is too large Yes Table 2.3: Summary of GL errors and defined as follows: GL_TABLE_TOO_LARGE_EXT 0x8031 Additions to Chapter 3 of the 1.0 specification (Rasterization) The specification of histogram and minmax operators is added to the GL Specification in section 3.6.2, "Pixel Transfer Modes." A histogram table is specified using the HistogramEXT command. Its <target> parameter must be HISTOGRAM_EXT if a histogram table is to be specified. (Optional target value PROXY_HISTOGRAM_EXT is described below.) Its <width> parameter, which must be a power of 2, specifies the number of entries in the histogram table, and its <internalformat> parameter specifies the format of each table entry. <sink> specifies whether pixel groups will be consumed by the histogram operation (TRUE) or passed on to the minmax operation (FALSE). The error INVALID_VALUE results if <width> is specified less than zero or is not a power of 2. The error TABLE_TOO_LARGE_EXT results if the specified histogram table is too large for the implementation. (See the PROXY discussion below.) The error INVALID_ENUM results if <internalformat> is not one of the values accepted by the <components> parameter of TexImage2D (as defined by EXT_texture), except that values 1, 2, 3, 4, INTENSITY_EXT, INTENSITY4_EXT, INTENSITY8_EXT, INTENSITY12_EXT, and INTENSITY16_EXT are not accepted. If no error results from the execution of HistogramEXT, the specified histogram table is redefined to have <width> entries, each with the specified internal format. The entries are indexed zero through N-1, where N is the <width> of the table. Each value in each entry is set to zero. The values in the previous histogram table, if any, are lost. It is acceptable for an implementation to vary its allocation of internal component resolution based any HistogramEXT parameter, but the allocation must not be a function of any other factor, and cannot be changed once it is established. In particular, allocations must be invariant -- the same allocation must be made each time a histogram is specified with the same parameter values. Provision is made for an application to determine what component resolutions are available without having to fully specify the histogram (see below). A minmax table is specified using the MinmaxEXT command. Its <target> parameter must be MINMAX_EXT. <internalformat> may be any of the token values accepted by the <components> parameter of TexImage2D, except that 1, 2, 3, 4, INTENSITY_EXT, INTENSITY4_EXT, INTENSITY8_EXT, INTENSITY12_EXT, and INTENSITY16_EXT are not accepted. <sink> is set to TRUE or FALSE. The resulting minmax table always has 2 entries, each with values corresponding only to the components of the internal format. The operations of the histogram and minmax are added to the GL Specification in section 3.6.3, "Rasterization of Pixel Rectangles, immediately following the subsection "Index Lookup", and immediately prior to the subsection "Final Conversion". Histogram and minmax operations are performed only for RGBA pixel groups, though these groups may have been specified as color indices and converted to RGBA by index table lookup. Histogram and minmax are enabled and disabled by calling Enable or Disable with HISTOGRAM_EXT or MINMAX_EXT passed as the <cap> parameter. If HISTOGRAM_EXT is enabled, and the pixel groups contain RGBA values, then indices Ri, Gi, Bi, and Ai are derived from the red, green, blue, and alpha components of each pixel group (without modifying these components) by clamping the components to [0,1], multiplying each by one less than the width of the histogram table, and rounding each to the nearest integer. If the format of the HISTOGRAM_EXT table includes red or luminance, the red or luminance component of histogram entry Ri is incremented by one. If the format of the HISTOGRAM_EXT table includes green, the green component of histogram entry Gi is incremented by one. The blue and alpha components of histogram entries Bi and Ai are incremented in the same way. If a histogram entry component is incremented beyond its maximum value, its value becomes undefined. (This is not an error.) If MINMAX_EXT is enabled, and the pixel groups contain RGBA values, then the red, green, blue, and alpha components of each group are compared to the minimum and maximum values for each, which are stored in the 2-element minmax table. (The first element stores the minimum values, the second stores the maximum values.) If the format of this table includes red or luminance, the red component value replaces the red or luminance value in the minimum table element if and only if it is less than that component. Likewise, if the format includes red or luminance and the red component of the group is greater than the red or luminance value in the maximum element, the red group component replaces the red or luminance maximum component. If the format of the table includes green, the green group component conditionally replaces the green minimum and/or maximum if it is smaller or larger, respectively. The blue and alpha group components are similarly tested and replaced, if the table format includes blue and/or alpha. The internal type of the minimum and maximum component values is floating point -- there are no semantics defined for the treatment of group component values that are outside the representable range of the minimum and maximum values. By default histogram and minmax operations have no effect on the stream of pixel groups being processed. If HISTOGRAM_EXT is enabled and the histogram <sink> parameter was specified as TRUE, however, all RGBA pixel groups are discarded immediately after the histogram operation is completed. Because histogram precedes minmax, no minmax operation is performed. No pixel fragments are generated, no change is made to texture memory contents, and no pixel values are returned. If MINMAX_EXT is enabled and the minmax <sink> parameter was specified as TRUE, all RGBA pixel groups are discarded immediately after the minmax operation is completed. Because minmax follows histogram, a histogram operation with <sink> set to FALSE may precede such a minmax operation. Again no pixel fragments are generated, no change is made to texture memory contents, and no pixel values are returned. The current contents of the histogram tables are queried using GetHistogramEXT. <target> must be HISTOGRAM_EXT. <format> must be one of RED, GREEN, BLUE, ALPHA, RGB, RGBA, ABGR_EXT, LUMINANCE, or LUMINANCE_ALPHA. <type> must be UNSIGNED_BYTE, BYTE, UNSIGNED_SHORT, SHORT, UNSIGNED_INT, INT, or FLOAT. A 1-dimensional image with the same width as the histogram is returned to <values>. No pixel transfer operations are performed on this image, but pixel storage modes that are applicable to 1-dimensional images are performed. Color components that are requested in the specified <format>, but which are not included in the internal format of the histogram, are returned as zero. The assignments of internal color components to the components requested by <format> are internal component resulting component ------------------ ------------------- red red green green blue blue alpha alpha luminance red <reset> is either TRUE or FALSE. If TRUE, each component counter that is actually returned is reset to zero. Counters that are not returned are not modified. All counters of all elements of histogram <target> are reset to zero when ResetHistogramEXT is called. <target> must be either HISTOGRAM_EXT. It is not an error to reset or query the contents of a histogram table with zero entries. The current contents of the minmax tables are queried using GetMinmaxEXT. <target> must be MINMAX_EXT. <format> must be one of RED, GREEN, BLUE, ALPHA, RGB, RGBA, ABGR_EXT, LUMINANCE, or LUMINANCE_ALPHA. <type> must be UNSIGNED_BYTE, BYTE, UNSIGNED_SHORT, SHORT, UNSIGNED_INT, INT, or FLOAT. A 1-dimensional image with width of 2 is returned to values. No pixel transfer operations are performed on this image, but pixel storage modes that are applicable to 1-dimensional images are performed. Color components that are requested in the specified <format>, but which are not included in the internal format of the minmax table, are returned as zero. The assignment of internal color components to the components requested by <format> are the same as for histogram return. <reset> is either TRUE or FALSE. If TRUE, each minimum value that is actually returned is reset to the maximum representable value, and each maximum value that is returned is reset to the minimum representable value. Minimum and maximum values that are not returned are not modified. All minimum and maximum values of minmax table <target> are reset to their maximum and minimum representable values, respectively, when ResetMinmaxEXT is called. <target> must be MINMAX_EXT. Query support ------------- Alternate sets of histogram state are defined for the proxy histogram PROXY_HISTOGRAM_EXT. When HistogramEXT is called with <target> set to PROXY_HISTOGRAM_EXT, proxy state values HISTOGRAM_WIDTH_EXT, HISTOGRAM_FORMAT, HISTOGRAM_RED_SIZE_EXT, HISTOGRAM_GREEN_SIZE_EXT, HISTOGRAM_BLUE_SIZE_EXT, HISTOGRAM_ALPHA_SIZE_EXT, and HISTOGRAM_LUMINANCE_SIZE_EXT are always recomputed and updated, even if the histogram is too large to actually be used. If the histogram is too large, all of these state variables are set to zero. If the histogram could be accommodated by Histogram called with <target> HISTOGRAM_EXT, these values are set as though HISTOGRAM_EXT were being defined. All of these state values can be queried with GetHistogramParameterivEXT or GetHistogramParameterfvEXT with <target> set to PROXY_HISTOGRAM_EXT. Calling HistogramEXT with <target> PROXY_HISTOGRAM_EXT has no effect on the actual histogram. There is no image associated with PROXY_HISTOGRAM_EXT. Therefore PROXY_HISTOGRAM_EXT cannot be used as a histogram, and its image must never be queried using GetHistogramEXT. (The error INVALID_ENUM results if this is attempted.) Additions to Chapter 4 of the 1.0 Specification (Per-Fragment Operations and the Framebuffer) The operation of histogram and minmax during pixel copy and query operations is identical to the operation during pixel drawing and texture image definition. Additions to Chapter 5 of the 1.0 Specification (Special Functions) GetHistogramEXT, GetHistogramParameterivEXT, GetHistogramParameterfvEXT, GetMinmaxEXT, GetMinmaxParameterivEXT, and GetMinmaxParameterfvEXT are not included in display lists -- they are executed immediately when called. Additions to Chapter 6 of the 1.0 Specification (State and State Requests) Integer and floating point query functions GetHistogramParameterivEXT and GetHistogramParameterfvEXT are provided. <target> must be HISTOGRAM_EXT or PROXY_HISTOGRAM_EXT. <pname> is one of HISTOGRAM_FORMAT_EXT, HISTOGRAM_WIDTH_EXT, HISTOGRAM_RED_SIZE_EXT, HISTOGRAM_GREEN_SIZE_EXT, HISTOGRAM_BLUE_SIZE_EXT, HISTOGRAM_ALPHA_SIZE_EXT, HISTOGRAM_LUMINANCE_SIZE_EXT, or HISTOGRAM_SINK_EXT. The value of the specified parameter is returned in <params>. Integer and floating point query functions GetMinmaxParameterivEXT and GetMinmaxParameterfvEXT are provided. <target> must be MINMAX_EXT. <pname> is MINMAX_FORMAT_EXT or MINMAX_SINK_EXT. The value of the specified parameter is returned in <params>. Additions to the GLX Specification None GLX Protocol Ten new GL commands are added. The following four rendering commands are sent to the server as part of a glXRender request: HistogramEXT 2 20 rendering command length 2 4110 rendering command opcode 4 ENUM target 4 INT32 width 4 ENUM internalformat 1 BOOL sink 3 unused ResetHistogramEXT 2 8 rendering command length 2 4112 rendering command opcode 4 ENUM target MinmaxEXT 2 16 rendering command length 2 4111 rendering command opcode 4 ENUM target 4 ENUM internalformat 1 BOOL sink 3 unused ResetMinmaxEXT 2 8 rendering command length 2 4113 rendering command opcode 4 ENUM target The remaining commands are non-rendering commands. These commands are sent separately (i.e., not as part of a glXRender or glXRenderLarge request), using the glXVendorPrivateWithReply request: GetHistogramEXT 1 CARD8 opcode (X assigned) 1 17 GLX opcode (glXVendorPrivateWithReply) 2 7 request length 4 5 vendor specific opcode 4 GLX_CONTEXT_TAG context tag 4 ENUM target 4 ENUM format 4 ENUM type 1 BOOL swap_bytes 1 BOOL reset 2 unused => 1 1 reply 1 unused 2 CARD16 sequence number 4 n reply length 24 unused 4*n LISTofBYTE pixels If <format> or <type> is not valid then the command is erroneous and n=0. The structure of <pixels> is described in Appendix A of the GLX Protocol Specification, "Pixel Data", using the parameters <swap_bytes>, <format>, and <type>. No extra padding is needed after <pixels> because the image format already pads to 32 bits. GetHistogramParameterfvEXT 1 CARD8 opcode (X assigned) 1 17 GLX opcode (glXVendorPrivateWithReply) 2 5 request length 4 6 vendor specific opcode 4 GLX_CONTEXT_TAG context tag 4 ENUM target 4 ENUM pname => 1 1 reply 1 unused 2 CARD16 sequence number 4 m reply length, m = (n==1 ? 0 : n) 4 unused 4 CARD32 n if (n=1) this follows: 4 INT32 params 12 unused otherwise this follows: 16 unused n*4 LISTofINT32 params Note that n may be zero, indicating that a GL error occurred. Also, n>1, is for future extensibility. GetHistogramParameterivEXT 1 CARD8 opcode (X assigned) 1 17 GLX opcode (glXVendorPrivateWithReply) 2 5 request length 4 7 vendor specific opcode 4 GLX_CONTEXT_TAG context tag 4 ENUM target 4 ENUM pname => 1 1 reply 1 unused 2 CARD16 sequence number 4 m reply length, m = (n==1 ? 0 : n) 4 unused 4 CARD32 n if (n=1) this follows: 4 INT32 params 12 unused otherwise this follows: 16 unused n*4 LISTofINT32 params Note that n may be zero, indicating that a GL error occurred. Also, n>1, is for future extensibility. GetMinmaxEXT 1 CARD8 opcode (X assigned) 1 17 GLX opcode (glXVendorPrivateWithReply) 2 7 request length 4 8 vendor specific opcode 4 GLX_CONTEXT_TAG context tag 4 ENUM target 4 ENUM format 4 ENUM type 1 BOOL swap_bytes 1 BOOL reset 2 unused => 1 1 reply 1 unused 2 CARD16 sequence number 4 n reply length 24 unused 4*n LISTofBYTE pixels If <format> or <type> is not valid then the command is erroneous and n=0. The structure of <pixels> is described in Appendix A of the GLX Protocol Specification, "Pixel Data", using the parameters <swap_bytes>, <format>, and <type>. No extra padding is needed after <pixels> because the image format already pads to 32 bits. GetMinmaxParameterfvEXT 1 CARD8 opcode (X assigned) 1 17 GLX opcode (glXVendorPrivateWithReply) 2 5 request length 4 9 vendor specific opcode 4 GLX_CONTEXT_TAG context tag 4 ENUM target 4 ENUM pname => 1 1 reply 1 unused 2 CARD16 sequence number 4 m reply length, m = (n==1 ? 0 : n) 4 unused 4 CARD32 n if (n=1) this follows: 4 INT32 params 12 unused otherwise this follows: 16 unused n*4 LISTofINT32 params Note that n may be zero, indicating that a GL error occurred. Also, n>1, is for future extensibility. GetMinmaxParameterivEXT 1 CARD8 opcode (X assigned) 1 17 GLX opcode (glXVendorPrivateWithReply) 2 5 request length 4 10 vendor specific opcode 4 GLX_CONTEXT_TAG context tag 4 ENUM target 4 ENUM pname => 1 1 reply 1 unused 2 CARD16 sequence number 4 m reply length, m = (n==1 ? 0 : n) 4 unused 4 CARD32 n if (n=1) this follows: 4 INT32 params 12 unused otherwise this follows: 16 unused n*4 LISTofINT32 params Note that n may be zero, indicating that a GL error occurred. Also, n>1, is for future extensibility. Dependencies on EXT_abgr If EXT_abgr is supported, the <format> parameters of GetHistogramEXT and GetMinmaxEXT accept ABGR_EXT. Otherwise they do not. Dependencies on EXT_texture EXT_texture is required. This extension builds on the notion of internal image format, which is defined by EXT_texture. Errors INVALID_ENUM is generated if HistogramEXT parameter <target> is not HISTOGRAM_EXT or PROXY_HISTOGRAM_EXT. INVALID_VALUE is generated if HistogramEXT parameter <width> is less than zero or is not a power of 2. INVALID_ENUM is generated if HistogramEXT parameter <internalformat> is not ALPHA, RGB, RGBA, LUMINANCE, LUMINANCE_ALPHA, or one of the tokens defined by the EXT_texture extension. (Values 1, 2, 3, and 4 are not accepted as internal formats by HistogramEXT). TABLE_TOO_LARGE_EXT is generated if HistogramEXT is called with parameter <target> of HISTOGRAM_EXT and the histogram as specified is too large for the implementation. INVALID_ENUM is generated if ResetHistogramEXT parameter <target> is not HISTOGRAM_EXT. INVALID_ENUM is generated if GetHistogramEXT parameter <target> is not HISTOGRAM_EXT. INVALID_ENUM is generated if GetHistogramEXT parameter <format> is not RED, GREEN, BLUE, ALPHA, RGB, RGBA, ABGR_EXT, LUMINANCE, or LUMINANCE_ALPHA. INVALID_ENUM is generated if GetHistogramEXT parameter <type> is not UNSIGNED_BYTE, BYTE, UNSIGNED_SHORT, SHORT, UNSIGNED_INT, INT, or FLOAT. INVALID_ENUM is generated if GetHistogramParameterivEXT or GetHistogramParameterfvEXT parameter <target> is not HISTOGRAM_EXT or PROXY_HISTOGRAM_EXT. INVALID_ENUM is generated if GetHistogramParameterivEXT or GetHistogramParameterfvEXT parameter <pname> is not HISTOGRAM_FORMAT_EXT, HISTOGRAM_WIDTH_EXT, HISTOGRAM_RED_SIZE_EXT, HISTOGRAM_GREEN_SIZE_EXT, HISTOGRAM_BLUE_SIZE_EXT, HISTOGRAM_ALPHA_SIZE_EXT, HISTOGRAM_LUMINANCE_SIZE_EXT, or HISTOGRAM_SINK_EXT. INVALID_OPERATION is generated if HistogramEXT, ResetHistogramEXT, GetHistogramEXT, GetHistogramParameterivEXT, or GetHistogramParameterfvEXT is called between execution of Begin and the corresponding execution of End. INVALID_ENUM is generated if MinmaxEXT parameter <target> is not MINMAX_EXT. INVALID_ENUM is generated if MinmaxEXT parameter <internalformat> is not ALPHA, RGB, RGBA, LUMINANCE, LUMINANCE_ALPHA, or one of the tokens defined by the EXT_texture extension. (Values 1, 2, 3, and 4 are not accepted as internal formats by MinmaxEXT). INVALID_ENUM is generated if ResetMinmaxEXT parameter <target> is not MINMAX_EXT. INVALID_ENUM is generated if GetMinmaxEXT parameter <target> is not MINMAX_EXT. INVALID_ENUM is generated if GetMinmaxEXT parameter <format> is not RED, GREEN, BLUE, ALPHA, RGB, RGBA, ABGR_EXT, LUMINANCE, or LUMINANCE_ALPHA. INVALID_ENUM is generated if GetMinmaxEXT parameter <type> is not UNSIGNED_BYTE, BYTE, UNSIGNED_SHORT, SHORT, UNSIGNED_INT, INT, or FLOAT. INVALID_ENUM is generated if GetMinmaxParameterivEXT or GetMinmaxParameterfvEXT parameter <target> is not MINMAX_EXT. INVALID_ENUM is generated if GetMinmaxParameterivEXT or GetMinmaxParameterfvEXT parameter <pname> is not MINMAX_FORMAT_EXT or MINMAX_SINK_EXT. INVALID_OPERATION is generated if MinmaxEXT, ResetMinmaxEXT, GetMinmaxEXT, GetMinmaxParameterivEXT, or GetMinmaxParameterfvEXT is called between execution of Begin and the corresponding execution of End. New State Get Value Get Command Type Initial Value Attribute --------- ----------- ---- ------------- --------- HISTOGRAM_EXT IsEnabled B False pixel/enable HISTOGRAM GetHistogramEXT I empty - HISTOGRAM_WIDTH_EXT GetHistogramParameterivEXT Z+ 0 - HISTOGRAM_FORMAT_EXT GetHistogramParameterivEXT Z33 RGBA - HISTOGRAM_RED_SIZE_EXT GetHistogramParameterivEXT Z+ 0 - HISTOGRAM_GREEN_SIZE_EXT GetHistogramParameterivEXT Z+ 0 - HISTOGRAM_BLUE_SIZE_EXT GetHistogramParameterivEXT Z+ 0 - HISTOGRAM_ALPHA_SIZE_EXT GetHistogramParameterivEXT Z+ 0 - HISTOGRAM_LUMINANCE_SIZE_EXT GetHistogramParameterivEXT Z+ 0 - HISTOGRAM_SINK_EXT GetHistogramParameterivEXT B False - MINMAX_EXT IsEnabled B False pixel/enable MINMAX GetMinmaxEXT Rn (M,M,M,M),(m,m,m,m) - MINMAX_FORMAT_EXT GetMinmaxParameterivEXT Z33 RGBA - MINMAX_SINK_EXT GetMinmaxParameterivEXT B False - Note, M and m are the maximum and minimum representable values of the minmax components. New Implementation Dependent State None