NOTES revision 1.1
1 1.1 mrg INTRODUCTION 2 1.1 mrg 3 1.1 mrg A generic, configurable software implementation of GL transformation & 4 1.1 mrg lighting. 5 1.1 mrg 6 1.1 mrg This module provides an implementation of the routines required by the 7 1.1 mrg 'vtxfmt' mechanism of core mesa for tnl functionality in all 8 1.1 mrg combinations of compile and execute modes. 9 1.1 mrg 10 1.1 mrg Most current drivers use the tnl module exclusively to provide this 11 1.1 mrg functionality. 12 1.1 mrg 13 1.1 mrg 14 1.1 mrg STATE 15 1.1 mrg 16 1.1 mrg To create and destroy the module: 17 1.1 mrg 18 1.1 mrg GLboolean _tnl_CreateContext( struct gl_context *ctx ); 19 1.1 mrg void _tnl_DestroyContext( struct gl_context *ctx ); 20 1.1 mrg 21 1.1 mrg The module is not active by default, and must be installed by calling 22 1.1 mrg _tnl_Wakeup(). This function installs internal tnl functions into all 23 1.1 mrg the vtxfmt dispatch hooks, thus taking over the task of transformation 24 1.1 mrg and lighting entirely: 25 1.1 mrg 26 1.1 mrg void _tnl_wakeup_exec( struct gl_context *ctx ); 27 1.1 mrg void _tnl_wakeup_save_exec( struct gl_context *ctx ); 28 1.1 mrg 29 1.1 mrg 30 1.1 mrg This module tracks state changes internally and maintains derived 31 1.1 mrg values based on the current state. For this to work, the driver 32 1.1 mrg ensure the following funciton is called whenever the state changes and 33 1.1 mrg the swsetup module is 'awake': 34 1.1 mrg 35 1.1 mrg void _tnl_InvalidateState( struct gl_context *ctx, GLuint new_state ); 36 1.1 mrg 37 1.1 mrg There is no explicit call to put the tnl module to sleep. Simply 38 1.1 mrg install other function pointers into all the vtxfmt dispatch slots, 39 1.1 mrg and (optionally) cease calling _tnl_InvalidateState(). 40 1.1 mrg 41 1.1 mrg CUSTOMIZATION 42 1.1 mrg 43 1.1 mrg The module provides customizability through several mechanisms. The 44 1.1 mrg most important is by allowing drivers to specify the pipeline through 45 1.1 mrg which vertex data is passed, including its eventual transfer to 46 1.1 mrg rasterization hardware (or software). 47 1.1 mrg 48 1.1 mrg The default pipeline is specified in t_pipeline.c, and is usually a 49 1.1 mrg starting point for driver pipelines. Some drivers will remove a stage 50 1.1 mrg where hardware provides support for the implemented operation (for 51 1.1 mrg instance fog where per-pixel hardware fog is available), 52 1.1 mrg or add stages to shortcircuit latter operations (for 53 1.1 mrg example taking advantage of hardware support for strips and other 54 1.1 mrg higher-level primitives (for example the radeon driver). 55 1.1 mrg 56 1.1 mrg In addition, the following functions provide further tweaks: 57 1.1 mrg 58 1.1 mrg extern void 59 1.1 mrg _tnl_need_projected_coords( struct gl_context *ctx, GLboolean flag ); 60 1.1 mrg 61 1.1 mrg - Direct the default vertex transformation stage to 62 1.1 mrg produce/not produce projected clip coordinates. 63 1.1 mrg 64 1.1 mrg extern void 65 1.1 mrg _tnl_need_dlist_loopback( struct gl_context *ctx, GLboolean flag ); 66 1.1 mrg 67 1.1 mrg - Direct the display list component of the tnl module to 68 1.1 mrg replay display lists as 'glVertex' type calls, rather than 69 1.1 mrg passing the display list data directly into the tnl pipeline 70 1.1 mrg mechanism. 71 1.1 mrg 72 1.1 mrg This allows display lists to be replayed by the tnl module 73 1.1 mrg even when the module is not strictly active. 74 1.1 mrg 75 1.1 mrg 76 1.1 mrg extern void 77 1.1 mrg _tnl_need_dlist_norm_lengths( struct gl_context *ctx, GLboolean flag ); 78 1.1 mrg 79 1.1 mrg - Direct the display list component to enable/disable caching 80 1.1 mrg 1/length values for display list normals. Doing so is 81 1.1 mrg ususally helpful when lighting is performed in software, but 82 1.1 mrg wasteful otherwise. 83 1.1 mrg 84 1.1 mrg 85 1.1 mrg DRIVER INTERFACE 86 1.1 mrg 87 1.1 mrg The module itself offers a minimal driver interface: 88 1.1 mrg 89 1.1 mrg void (*RunPipeline)( struct gl_context *ctx ); 90 1.1 mrg 91 1.1 mrg Normally this is set to _tnl_RunPipeline(), however the driver can use 92 1.1 mrg this hook to wrap checks or other code around this call. 93 1.1 mrg 94 1.1 mrg In addition, the driver interface for the default render pipeline 95 1.1 mrg stage is housed in the tnl context struct (this could be cleaner). 96 1.1 mrg 97 1.1 mrg 98 1.1 mrg RENDER DRIVER INTERFACE 99 1.1 mrg 100 1.1 mrg See t_context.h for the definition and explanation of this.
Indexes created Tue Oct 27 00:25:24 UTC 2026