diff options
Diffstat (limited to 'mesalib/src/mesa/tnl/NOTES')
-rw-r--r-- | mesalib/src/mesa/tnl/NOTES | 200 |
1 files changed, 99 insertions, 101 deletions
diff --git a/mesalib/src/mesa/tnl/NOTES b/mesalib/src/mesa/tnl/NOTES index 9a35e948b..43c469201 100644 --- a/mesalib/src/mesa/tnl/NOTES +++ b/mesalib/src/mesa/tnl/NOTES @@ -1,102 +1,100 @@ -INTRODUCTION
-
-A generic, configurable software implementation of GL transformation &
-lighting.
-
-This module provides an implementation of the routines required by the
-'vtxfmt' mechanism of core mesa for tnl functionality in all
-combinations of compile and execute modes.
-
-Most current drivers use the tnl module exclusively to provide this
-functionality, though there is an experimental alternate
-implementation provided by the tnl_dd/t_dd_imm_* files which can
-handle a small subset of GL states in execute mode only.
-
-
-STATE
-
-To create and destroy the module:
-
- GLboolean _tnl_CreateContext( struct gl_context *ctx );
- void _tnl_DestroyContext( struct gl_context *ctx );
-
-The module is not active by default, and must be installed by calling
-_tnl_Wakeup(). This function installs internal tnl functions into all
-the vtxfmt dispatch hooks, thus taking over the task of transformation
-and lighting entirely:
-
- void _tnl_wakeup_exec( struct gl_context *ctx );
- void _tnl_wakeup_save_exec( struct gl_context *ctx );
-
-
-This module tracks state changes internally and maintains derived
-values based on the current state. For this to work, the driver
-ensure the following funciton is called whenever the state changes and
-the swsetup module is 'awake':
-
- void _tnl_InvalidateState( struct gl_context *ctx, GLuint new_state );
-
-There is no explicit call to put the tnl module to sleep. Simply
-install other function pointers into all the vtxfmt dispatch slots,
-and (optionally) cease calling _tnl_InvalidateState().
-
-CUSTOMIZATION
-
-The module provides customizability through several mechanisms. The
-most important is by allowing drivers to specify the pipeline through
-which vertex data is passed, including its eventual transfer to
-rasterization hardware (or software).
-
-The default pipeline is specified in t_pipeline.c, and is usually a
-starting point for driver pipelines. Some drivers will remove a stage
-where hardware provides support for the implemented operation (for
-instance fog where per-pixel hardware fog is available, as in the dri
-tdfx driver), or add stages to shortcircuit latter operations (for
-example taking advantage of hardware support for strips and other
-higher-level primitives (for example the radeon driver).
-
-In addition, the following functions provide further tweaks:
-
-extern void
-_tnl_need_projected_coords( struct gl_context *ctx, GLboolean flag );
-
- - Direct the default vertex transformation stage to
- produce/not produce projected clip coordinates.
-
-extern void
-_tnl_need_dlist_loopback( struct gl_context *ctx, GLboolean flag );
-
- - Direct the display list component of the tnl module to
- replay display lists as 'glVertex' type calls, rather than
- passing the display list data directly into the tnl pipeline
- mechanism.
-
- This allows display lists to be replayed by the tnl module
- even when the module is not strictly active.
-
-
-extern void
-_tnl_need_dlist_norm_lengths( struct gl_context *ctx, GLboolean flag );
-
- - Direct the display list component to enable/disable caching
- 1/length values for display list normals. Doing so is
- ususally helpful when lighting is performed in software, but
- wasteful otherwise.
-
-
-DRIVER INTERFACE
-
-The module itself offers a minimal driver interface:
-
- void (*RunPipeline)( struct gl_context *ctx );
-
-Normally this is set to _tnl_RunPipeline(), however the driver can use
-this hook to wrap checks or other code around this call.
-
-In addition, the driver interface for the default render pipeline
-stage is housed in the tnl context struct (this could be cleaner).
-
-
-RENDER DRIVER INTERFACE
-
+INTRODUCTION + +A generic, configurable software implementation of GL transformation & +lighting. + +This module provides an implementation of the routines required by the +'vtxfmt' mechanism of core mesa for tnl functionality in all +combinations of compile and execute modes. + +Most current drivers use the tnl module exclusively to provide this +functionality. + + +STATE + +To create and destroy the module: + + GLboolean _tnl_CreateContext( struct gl_context *ctx ); + void _tnl_DestroyContext( struct gl_context *ctx ); + +The module is not active by default, and must be installed by calling +_tnl_Wakeup(). This function installs internal tnl functions into all +the vtxfmt dispatch hooks, thus taking over the task of transformation +and lighting entirely: + + void _tnl_wakeup_exec( struct gl_context *ctx ); + void _tnl_wakeup_save_exec( struct gl_context *ctx ); + + +This module tracks state changes internally and maintains derived +values based on the current state. For this to work, the driver +ensure the following funciton is called whenever the state changes and +the swsetup module is 'awake': + + void _tnl_InvalidateState( struct gl_context *ctx, GLuint new_state ); + +There is no explicit call to put the tnl module to sleep. Simply +install other function pointers into all the vtxfmt dispatch slots, +and (optionally) cease calling _tnl_InvalidateState(). + +CUSTOMIZATION + +The module provides customizability through several mechanisms. The +most important is by allowing drivers to specify the pipeline through +which vertex data is passed, including its eventual transfer to +rasterization hardware (or software). + +The default pipeline is specified in t_pipeline.c, and is usually a +starting point for driver pipelines. Some drivers will remove a stage +where hardware provides support for the implemented operation (for +instance fog where per-pixel hardware fog is available), +or add stages to shortcircuit latter operations (for +example taking advantage of hardware support for strips and other +higher-level primitives (for example the radeon driver). + +In addition, the following functions provide further tweaks: + +extern void +_tnl_need_projected_coords( struct gl_context *ctx, GLboolean flag ); + + - Direct the default vertex transformation stage to + produce/not produce projected clip coordinates. + +extern void +_tnl_need_dlist_loopback( struct gl_context *ctx, GLboolean flag ); + + - Direct the display list component of the tnl module to + replay display lists as 'glVertex' type calls, rather than + passing the display list data directly into the tnl pipeline + mechanism. + + This allows display lists to be replayed by the tnl module + even when the module is not strictly active. + + +extern void +_tnl_need_dlist_norm_lengths( struct gl_context *ctx, GLboolean flag ); + + - Direct the display list component to enable/disable caching + 1/length values for display list normals. Doing so is + ususally helpful when lighting is performed in software, but + wasteful otherwise. + + +DRIVER INTERFACE + +The module itself offers a minimal driver interface: + + void (*RunPipeline)( struct gl_context *ctx ); + +Normally this is set to _tnl_RunPipeline(), however the driver can use +this hook to wrap checks or other code around this call. + +In addition, the driver interface for the default render pipeline +stage is housed in the tnl context struct (this could be cleaner). + + +RENDER DRIVER INTERFACE + See t_context.h for the definition and explanation of this.
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