| Name |
| |
| NV_internalformat_sample_query |
| |
| Name Strings |
| |
| GL_NV_internalformat_sample_query |
| |
| Contact |
| |
| Daniel Koch, NVIDIA (dkoch 'at' nvidia.com) |
| |
| Contributors |
| |
| Piers Daniell, NVIDIA |
| Weiwan Liu, NVIDIA |
| |
| Status |
| |
| Complete |
| |
| Version |
| |
| Last Modified Date: October 10, 2014 |
| Revision: 2 |
| |
| Number |
| |
| OpenGL Extension #475 |
| OpenGL ES Extension #196 |
| |
| Dependencies |
| |
| This specification is written against the OpenGL 4.5 (Core Profile) |
| Specification (September 19, 2014). |
| |
| OpenGL 4.2 or ARB_internalformat_query are required for an OpenGL |
| implementation. |
| |
| OpenGL ES 3.0 is required for an OpenGL ES implementation. |
| |
| This extension interacts with OpenGL ES 3.1. |
| |
| This extension interacts with KHR_debug and OpenGL 4.3. |
| |
| This extension interacts with OES_texture_storage_multisample_2d_array. |
| |
| Overview |
| |
| Some OpenGL implementations support modes of multisampling which have |
| properties which are non-obvious to applications and/or which may not be |
| standards conformant. The idea of non-conformant AA modes is not new, |
| and is exposed in both GLX and EGL with config caveats and the |
| GLX_NON_CONFORMANT_CONFIG for GLX and EGL_NON_CONFORMANT_CONFIG for EGL, |
| or by querying the EGL_CONFORMANT attribute in newer versions of EGL. |
| |
| Both of these mechanisms operate on a per-config basis, which works as |
| intended for window-based configs. However, with the advent of |
| application-created FBOs, it is now possible to do all the multisample |
| operations in an application-created FBO and never use a multisample |
| window. |
| |
| This extension further extends the internalformat query mechanism |
| (first introduced by ARB_internalformat_query and extended in |
| ARB_internalformat_query2) and introduces a mechanism for a |
| implementation to report properties of formats that may also be |
| dependent on the number of samples. This includes information |
| such as whether the combination of format and samples should be |
| considered conformant. This enables an implementation to report |
| caveats which might apply to both window and FBO-based rendering |
| configurations. |
| |
| Some NVIDIA drivers support multisample modes which are internally |
| implemented as a combination of multisampling and automatic |
| supersampling in order to obtain a higher level of anti-aliasing than |
| can be directly supported by hardware. This extension allows those |
| properties to be queried by an application with the MULTISAMPLES_NV, |
| SUPERSAMPLE_SCALE_X_NV and SUPERSAMPLE_SCALE_Y_NV properties. For |
| example, a 16xAA mode might be implemented by using 4 samples and |
| up-scaling by a factor of 2 in each of the x- and y-dimensions. |
| In this example, the driver might report MULTSAMPLES_NV of 4, |
| SUPERSAMPLE_SCALE_X_NV of 2, SUPERSAMPLE_SCALE_Y_NV of 2 and |
| CONFORMANT_NV of FALSE. |
| |
| |
| New Procedures and Functions |
| |
| void GetInternalformatSampleivNV(enum target, enum internalformat, |
| sizei samples, enum pname, |
| sizei bufSize, int *params); |
| |
| New Types |
| |
| None. |
| |
| New Tokens |
| |
| Accepted by the <target> parameter of GetInternalformatSampleivNV: |
| |
| RENDERBUFFER |
| TEXTURE_2D_MULTISAMPLE |
| TEXTURE_2D_MULTISAMPLE_ARRAY |
| |
| Accepted by the <pname> parameter of GetInternalformatSampleivNV: |
| |
| MULTISAMPLES_NV 0x9371 |
| SUPERSAMPLE_SCALE_X_NV 0x9372 |
| SUPERSAMPLE_SCALE_Y_NV 0x9373 |
| CONFORMANT_NV 0x9374 |
| |
| |
| Additions to Chapter 22 of the OpenGL 4.5 (Core Profile) Specification |
| (Context State Queries) |
| |
| Add a new section 22.3.ifsq "Internal Format Sample Queries": |
| |
| Information about implementation-dependent support for sample related |
| properties of internal formats can be queried with the command |
| |
| void GetInternalformatSampleivNV(enum target, enum internalformat, |
| sizei samples, enum pname, |
| sizei bufSize, int *params); |
| |
| <internalformat> must be color-renderable, depth-renderable, or |
| stencil-renderable (as defined in section 9.4). |
| |
| <target> indicates the usage of the <internalformat>, and must be one of |
| the targets that can be used for multisample resources, that is one of |
| RENDERBUFFER, TEXTURE_2D_MULTISAMPLE, or TEXTURE_2D_MULTISAMPLE_ARRAY. |
| |
| <samples> indicates the number of samples of the <internalformat> for |
| which properties are being queried. It is an error if the requested |
| <samples> are not supported for requested <internalformat> and <target>. |
| GetInternalformativ with the SAMPLES property can be used to determine |
| if <samples> is supported. |
| |
| No more than <bufSize> integers will be written into <params>. If |
| more data are available, they will be ignored and no error will be |
| generated. |
| |
| <pname> indicates the information to query, and it is one of the |
| following values. When a known property is queried, the associated |
| value is written into <params>, otherwise <params> is unmodified. |
| |
| - MULTISAMPLES_NV: returns the number of multisamples used when a |
| resource of the requested type and the specified <samples> is created. |
| |
| - SUPERSAMPLE_SCALE_X_NV: returns the super-sample scaling factor that |
| is used in the X-dimension when a resource of the requested type and |
| the specified <samples> is created. |
| |
| - SUPERSAMPLE_SCALE_Y_NV: returns the super-sample scaling factor that |
| is used in the Y-dimension when a resource of the requested type and |
| the specified <samples> is created. |
| |
| - CONFORMANT_NV: returns the conformance-compliance of a resource |
| created with the requested type and the specified <samples>. |
| TRUE is returned if the format/sample combination is supported in a |
| compliant manner. FALSE is returned if the requested format/sample |
| combination is not conformant. If this query reports |
| non-conformant status and the debug output functionality is enabled, |
| the GL will generate a debug output message describing the caveats. |
| The message has the source DEBUG_SOURCE_API, the type |
| DEBUG_TYPE_UNDEFINED_BEHAVIOR, and an implementation-dependent ID. |
| |
| Errors: |
| The INVALID_ENUM error is generated if <target> is not one of |
| RENDERBUFFER, TEXTURE_2D_MULTISAMPLE, or TEXTURE_2D_MULTISAMPLE_ARRAY. |
| |
| The INVALID_ENUM error is generated if <internalformat> is not |
| color-, depth-, or stencil-renderable. |
| |
| The INVALID_ENUM error is generated if <pname> is not one of |
| MULTISAMPLES_NV, SUPERSAMPLE_SCALE_X_NV, SUPERSAMPLE_SCALE_Y_NV, or |
| CONFORMANT_NV. |
| |
| The INVALID_VALUE error is generated if <bufSize> is negative. |
| |
| The INVALID_OPERATION error is generated if a resource of the requested |
| type and samples is not supported by the implementation. |
| |
| Additions to the WGL/GLX/EGL Specification |
| |
| None. |
| |
| Dependencies on OpenGL ES 3.1 |
| |
| If OpenGL ES 3.1 is not supported in an OpenGL ES implementation, |
| ignore references to TEXTURE_2D_MULTISAMPLE <target> and resources. |
| |
| Dependencies on OES_texture_storage_multisample_2d_array. |
| |
| If OES_texture_storage_multisample_2d_array is not supported in an |
| OpenGL ES implementation, ignore references to |
| TEXTURE_2D_MULTISAMPLE_ARRAY. If the extension is supported, replace |
| references to TEXTURE_2D_MULTISAMPLE_ARRAY with references to |
| TEXTURE_2D_MULTISAMPLE_ARRAY_OES. |
| |
| Dependencies on KHR_debug |
| |
| If KHR_debug or OpenGL 4.3 are not supported, ignore references to |
| debug output functionality. If KHR_debug is supported in an OpenGL ES |
| context, append the _KHR suffix onto associated types. |
| |
| New State |
| |
| None. |
| |
| Sample Code |
| |
| // Obtain supported sample count for a format: |
| GLint num_sample_counts = 0; |
| GLenum ifmt = GL_RGBA8; |
| GLenum target = GL_TEXTURE_2D_MULTISAMPLE; |
| glGetInternalformativ(target, ifmt, NUM_SAMPLE_COUNTS, 1, |
| &num_sample_counts); |
| |
| // get the list of supported samples for this format |
| GLint samples[num_sample_counts]; |
| glGetInternalformativ(target, ifmt, SAMPLES, num_sample_counts, samples); |
| |
| // loop over the supported formats and get per-sample properties |
| for (int i=0; i<num_sample_counts; i++) |
| { |
| GLint multisample; |
| GLint ss_scale_x, ss_scale_y; |
| GLint conformant; |
| glGetInternalformatSampleivNV(target, ifmt, samples[i], |
| GL_MULTISAMPLES_NV, |
| 1, &multisample); |
| glGetInternalformatSampleivNV(target, ifmt, samples[i], |
| GL_SUPERSAMPLE_SCALE_X_NV, |
| 1, &ss_scale_x); |
| glGetInternalformatSampleivNV(target, ifmt, samples[i], |
| GL_SUPERSAMPLE_SCALE_Y_NV, |
| 1, &ss_scale_y); |
| glGetInternalformatSampleivNV(target, ifmt, samples[i], |
| GL_CONFORMANT_NV, 1, &conformant); |
| // do something with this information :-) |
| } |
| |
| |
| Conformance Tests |
| |
| TBD |
| |
| Issues |
| |
| None yet! |
| |
| |
| Revision History |
| |
| Rev. Date Author Changes |
| ---- -------- -------- ----------------------------------------- |
| 1 09/24/14 dkoch Initial version |
| 2 10/10/14 weiwliu Assign value to new tokens |
