reactos/dll/opengl/mesa/src/mesa/swrast_setup/NOTES

   1 INTRODUCTION
   2
   3 A helper module which provides glue to bind the software rasterizer to
   4 the software t&l module.  The main task of this module is to build
   5 swrast vertices from the t&l vertex_buffer structs, and to use them to
   6 perform triangle setup functions not implemented in the software
   7 rasterizer.
   8
   9 The module implements a full set of functions to plug into the
  10 t_vb_render.c driver interface (tnl->Driver.Render.*).
  11
  12 There are strong advantages to decoupling the software rasterizer from
  13 the t&l module, primarily allowing hardware drivers better control
  14 over fallbacks, the removal of implicit knowledge about the software
  15 rasterizer in the t&l module, allowing the two modules to evolve
  16 independently and allowing either to be substituted with equivalent
  17 functionality from another codebase.
  18
  19 This module implements triangle/quad setup for offset, unfilled and
  20 twoside-lit triangles.  The software rasterizer doesn't handle these
  21 primitives directly.
  22
  23 Hardware rasterization drivers typically use this module in situations
  24 where no hardware rasterization is possible, ie during total
  25 fallbacks.
  26
  27 STATE
  28
  29 To create and destroy the module:
  30
  31         GLboolean _swsetup_CreateContext( struct gl_context *ctx );
  32         void _swsetup_DestroyContext( struct gl_context *ctx );
  33
  34 The module is not active by default, and must be installed by calling
  35 _swrast_Wakeup().  This function installs internal swrast_setup
  36 functions into all the tnl->Driver.Render driver hooks, thus taking
  37 over the task of rasterization entirely:
  38
  39         void _swrast_Wakeup( struct gl_context *ctx );
  40
  41
  42 This module tracks state changes internally and maintains derived
  43 values based on the current state.  For this to work, the driver
  44 ensure the following funciton is called whenever the state changes and
  45 the swsetup module is 'awake':
  46
  47         void _swsetup_InvalidateState( struct gl_context *ctx, GLuint new_state );
  48
  49 There is no explicit call to put the swsetup module to sleep.  Simply
  50 install other function pointers into all the tnl->Driver.Render.*
  51 hooks, and (optionally) cease calling _swsetup_InvalidateState().
  52
  53 DRIVER INTERFACE
  54
  55 The module offers a minimal driver interface:
  56
  57          void (*Start)( struct gl_context *ctx );
  58          void (*Finish)( struct gl_context *ctx );
  59
  60 These are called before and after the completion of all swrast drawing
  61 activity.  As swrast doesn't call callbacks during triangle, line or
  62 point rasterization, these are necessary to provide locking hooks for
  63 some drivers.  They may otherwise be left null.
  64
  65