Crazy Mixed-Up Leo Rendering Code from Header Files

In the $XGLHOME/src/dd/leo/include directory there are some strange
header files:

Leo3dLi1MspRend.h           Leo3dLi1TlistRend.h
Leo3dLi1TStripStarRend.h    Leo3dLi1TlistRestartRend.h
Leo3dLi1TlistGenlRend.h

These files contain template code used by the .cc files to generate
specialized renderers for specific cases.  This keeps the program
from having to do 'if (lighting == FACET) . . . ' which will
slow down the renderer.  It also keeps the programmer from having
to repeat the same code several times for several specific cases.
The drawback is that the code is hard to debug because you can't
set breakpoints in it.

The renderers are chosen by using a jump table.  This is a table of
function pointers to renderers.  Each different combination of
rendering options leads to a different entry in the table by using
a simple algorithm (from Leo3dLi1Msp.cc):

           index = sp->surf.copy_facet * 20 +
                   sp->surf.rend_color_src * 5 +
                   sp->surf.rend_norm_src;
         
           sp->surf.renderer->msp = mspRenderer[index];

The array is filled with pointers to generic renderers for most
cases, but some specific (well used) combinations have their own
renderer (from Leo3dLi1Msp.cc):


static int (XglDpCtx3dLeo::*mspRenderer[40])(XglPrimData* pd) = {
/* copy_facet rend_color_src  rend_norm_src          renderer   */

/*FALSE CTX_COLOR          NO_NORMAL          */ XglDpCtx3dLeo::renderMsp,
/*FALSE CTX_COLOR          FACET_NORMAL       */ XglDpCtx3dLeo::renderMspCcFn,
/*FALSE CTX_COLOR          CALC_NORMAL        */ XglDpCtx3dLeo::renderMsp,
/*FALSE CTX_COLOR          VERTEX_NORMAL      */ XglDpCtx3dLeo::renderMspCcVn,
/*FALSE CTX_COLOR          FIRST_VERTEX_NORMAL*/ XglDpCtx3dLeo::renderMsp,
/*FALSE FACET_COLOR        NO_NORMAL          */ XglDpCtx3dLeo::renderMsp,
/*FALSE FACET_COLOR        FACET_NORMAL       */ XglDpCtx3dLeo::renderMsp,
/*FALSE FACET_COLOR        CALC_NORMAL        */ XglDpCtx3dLeo::renderMsp,
/*FALSE FACET_COLOR        VERTEX_NORMAL      */ XglDpCtx3dLeo::renderMsp,
/*FALSE FACET_COLOR        FIRST_VERTEX_NORMAL*/ XglDpCtx3dLeo::renderMsp,
/*FALSE VERTEX_COLOR       NO_NORMAL          */ XglDpCtx3dLeo::renderMspVcNn,
/*FALSE VERTEX_COLOR       FACET_NORMAL       */ XglDpCtx3dLeo::renderMsp,
/*FALSE VERTEX_COLOR       CALC_NORMAL        */ XglDpCtx3dLeo::renderMsp,
/*FALSE VERTEX_COLOR       VERTEX_NORMAL      */ XglDpCtx3dLeo::renderMsp,
/*FALSE VERTEX_COLOR       FIRST_VERTEX_NORMAL*/ XglDpCtx3dLeo::renderMsp,
/*FALSE FIRST_VERTEX_COLOR NO_NORMAL          */ XglDpCtx3dLeo::renderMsp,
/*FALSE FIRST_VERTEX_COLOR FACET_NORMAL       */ XglDpCtx3dLeo::renderMsp,
/*FALSE FIRST_VERTEX_COLOR CALC_NORMAL        */ XglDpCtx3dLeo::renderMsp,
/*FALSE FIRST_VERTEX_COLOR VERTEX_NORMAL      */ XglDpCtx3dLeo::renderMsp,
/*FALSE FIRST_VERTEX_COLOR FIRST_VERTEX_NORMAL*/ XglDpCtx3dLeo::renderMsp,
/*TRUE  CTX_COLOR          NO_NORMAL          */ XglDpCtx3dLeo::renderMsp,
/*TRUE  CTX_COLOR          FACET_NORMAL       */ XglDpCtx3dLeo::renderMsp,
/*TRUE  CTX_COLOR          CALC_NORMAL        */ XglDpCtx3dLeo::renderMsp,
/*TRUE  CTX_COLOR          VERTEX_NORMAL      */ XglDpCtx3dLeo::renderMspCfCcVn,
/*TRUE  CTX_COLOR          FIRST_VERTEX_NORMAL*/ XglDpCtx3dLeo::renderMsp,
/*TRUE  FACET_COLOR        NO_NORMAL          */ XglDpCtx3dLeo::renderMsp,
/*TRUE  FACET_COLOR        FACET_NORMAL       */ XglDpCtx3dLeo::renderMsp,
/*TRUE  FACET_COLOR        CALC_NORMAL        */ XglDpCtx3dLeo::renderMsp,
/*TRUE  FACET_COLOR        VERTEX_NORMAL      */ XglDpCtx3dLeo::renderMsp,
/*TRUE  FACET_COLOR        FIRST_VERTEX_NORMAL*/ XglDpCtx3dLeo::renderMsp,
/*TRUE  VERTEX_COLOR       NO_NORMAL          */ XglDpCtx3dLeo::renderMspCfVcNn,
/*TRUE  VERTEX_COLOR       FACET_NORMAL       */ XglDpCtx3dLeo::renderMsp,
/*TRUE  VERTEX_COLOR       CALC_NORMAL        */ XglDpCtx3dLeo::renderMsp,
/*TRUE  VERTEX_COLOR       VERTEX_NORMAL      */ XglDpCtx3dLeo::renderMsp,
/*TRUE  VERTEX_COLOR       FIRST_VERTEX_NORMAL*/ XglDpCtx3dLeo::renderMsp,
/*TRUE  FIRST_VERTEX_COLOR NO_NORMAL          */ XglDpCtx3dLeo::renderMsp,
/*TRUE  FIRST_VERTEX_COLOR FACET_NORMAL       */ XglDpCtx3dLeo::renderMsp,
/*TRUE  FIRST_VERTEX_COLOR CALC_NORMAL        */ XglDpCtx3dLeo::renderMsp,
/*TRUE  FIRST_VERTEX_COLOR VERTEX_NORMAL      */ XglDpCtx3dLeo::renderMsp,
/*TRUE  FIRST_VERTEX_COLOR FIRST_VERTEX_NORMAL*/ XglDpCtx3dLeo::renderMsp
};


Notice how some lines are different.  Here's the code that generates
those specialized renderers:


#define MSP_FUNC_NAME renderMspCcFn
#define LEO_CTX_COLOR 
#define LEO_FACET_NORMAL
#include "include/Leo3dLi1MspRend.h"
#undef MSP_FUNC_NAME  
#undef LEO_CTX_COLOR
#undef LEO_FACET_NORMAL

#define MSP_FUNC_NAME renderMspCcVn
#define LEO_DIRECT_DMA_CHECK
#define LEO_CTX_COLOR 
#define LEO_VERTEX_NORMAL
#include "include/Leo3dLi1MspRend.h"
#undef MSP_FUNC_NAME  
#undef LEO_DIRECT_DMA_CHECK
#undef LEO_CTX_COLOR  
#undef LEO_VERTEX_NORMAL

#define MSP_FUNC_NAME renderMspVcNn
#define LEO_DIRECT_DMA_CHECK
#define LEO_VERTEX_COLOR
#define LEO_NO_NORMAL 
#include "include/Leo3dLi1MspRend.h"
#undef MSP_FUNC_NAME  
#undef LEO_DIRECT_DMA_CHECK
#undef LEO_VERTEX_COLOR
#undef LEO_NO_NORMAL  

#define MSP_FUNC_NAME renderMspCfCcVn
#define LEO_COPY_FACET
#define LEO_CTX_COLOR
#define LEO_VERTEX_NORMAL
#include "include/Leo3dLi1MspRend.h"
#undef MSP_FUNC_NAME  
#undef LEO_COPY_FACET
#undef LEO_CTX_COLOR
#undef LEO_VERTEX_NORMAL

#define MSP_FUNC_NAME renderMspCfVcNn
#define LEO_COPY_FACET
#define LEO_VERTEX_COLOR
#define LEO_NO_NORMAL 
#include "include/Leo3dLi1MspRend.h"
#undef MSP_FUNC_NAME  
#undef LEO_COPY_FACET
#undef LEO_VERTEX_COLOR
#undef LEO_NO_NORMAL  


So you can tell what's going on.  First is the name of the function
you want generated, then which attributes you want generated.  Here's
how the header file looks:


int
XglDpCtx3dLeo::MSP_FUNC_NAME(XglPrimData *pd)
{
   Leo_surface_props*          sp = cache->csp;  // Current surface props
   Xgli_api_data*              api_data;         // Api data
   Xgli_api_point_data*        pdata;            // Api point data

#if defined (LEO_COPY_FACET) || defined(LEO_FACET_NORMAL) || 
defined(LEO_FACET_COLOR)
   Xgli_api_facet_data*        fdata;            // Api facet data
#endif

   Xgl_pt_list*                pl;               // Current point list

#ifdef LEO_CALC_NORMAL
   Xgl_pt_f3d*                 cnorms = NULL;    // Steps through calcd normals
   Xgl_pt_f3d*                 cnorm_list = NULL;
#endif

#if defined (LEO_COPY_FACET) || defined(LEO_FACET_NORMAL) || 
defined(LEO_FACET_COLOR)
   char*                       facets = NULL;    // steps through api facets
#endif

[. . .]

-Paul