From 1e723abc27bdc2ad675bce79467a7308c2966861 Mon Sep 17 00:00:00 2001 From: marha Date: Tue, 22 Dec 2009 18:34:14 +0000 Subject: Forgotten files in previous commit --- mesalib/src/mesa/swrast_setup/NOTES | 65 +++++++++++++++++++++++++++++++++++++ 1 file changed, 65 insertions(+) create mode 100644 mesalib/src/mesa/swrast_setup/NOTES (limited to 'mesalib/src/mesa/swrast_setup/NOTES') diff --git a/mesalib/src/mesa/swrast_setup/NOTES b/mesalib/src/mesa/swrast_setup/NOTES new file mode 100644 index 000000000..c6cb4ab34 --- /dev/null +++ b/mesalib/src/mesa/swrast_setup/NOTES @@ -0,0 +1,65 @@ +INTRODUCTION + +A helper module which provides glue to bind the software rasterizer to +the software t&l module. The main task of this module is to build +swrast vertices from the t&l vertex_buffer structs, and to use them to +perform triangle setup functions not implemented in the software +rasterizer. + +The module implements a full set of functions to plug into the +t_vb_render.c driver interface (tnl->Driver.Render.*). + +There are strong advantages to decoupling the software rasterizer from +the t&l module, primarily allowing hardware drivers better control +over fallbacks, the removal of implicit knowledge about the software +rasterizer in the t&l module, allowing the two modules to evolve +independently and allowing either to be substituted with equivalent +functionality from another codebase. + +This module implements triangle/quad setup for offset, unfilled and +twoside-lit triangles. The software rasterizer doesn't handle these +primitives directly. + +Hardware rasterization drivers typically use this module in situations +where no hardware rasterization is possible, ie during total +fallbacks. + +STATE + +To create and destroy the module: + + GLboolean _swsetup_CreateContext( GLcontext *ctx ); + void _swsetup_DestroyContext( GLcontext *ctx ); + +The module is not active by default, and must be installed by calling +_swrast_Wakeup(). This function installs internal swrast_setup +functions into all the tnl->Driver.Render driver hooks, thus taking +over the task of rasterization entirely: + + void _swrast_Wakeup( GLcontext *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 _swsetup_InvalidateState( GLcontext *ctx, GLuint new_state ); + +There is no explicit call to put the swsetup module to sleep. Simply +install other function pointers into all the tnl->Driver.Render.* +hooks, and (optionally) cease calling _swsetup_InvalidateState(). + +DRIVER INTERFACE + +The module offers a minimal driver interface: + + void (*Start)( GLcontext *ctx ); + void (*Finish)( GLcontext *ctx ); + +These are called before and after the completion of all swrast drawing +activity. As swrast doesn't call callbacks during triangle, line or +point rasterization, these are necessary to provide locking hooks for +some drivers. They may otherwise be left null. + + -- cgit v1.2.3