#include "main/glheader.h"
#include "main/imports.h"
#include "sp_context.h"
#include "sp_headers.h"
#include "sp_surface.h"
#include "sp_quad.h"


/**
 * Loop over colorbuffers, passing quad to next stage each time.
 */
static void
cbuf_loop_quad(struct quad_stage *qs, struct quad_header *quad)
{
   struct softpipe_context *softpipe = qs->softpipe;
   const GLuint sz = sizeof(quad->outputs.color);
   GLfloat tmp[4][QUAD_SIZE];
   GLuint i;

   assert(sz == sizeof(tmp));

   /* make copy of original colors since they can get modified
    * by blending and masking.
    */
   memcpy(tmp, quad->outputs.color, sz);

   for (i = 0; i < softpipe->framebuffer.num_cbufs; i++) {
      /* set current cbuffer */
      softpipe->cbuf = softpipe->framebuffer.cbufs[i];

      /* pass blended quad to next stage */
      qs->next->run(qs->next, quad);

      if (i + 1 < softpipe->framebuffer.num_cbufs) {
         /* restore quad's colors for next buffer */
         memcpy(quad->outputs.color, tmp, sz);
      }
   }

   softpipe->cbuf = NULL; /* prevent accidental use */
}


/**
 * Create the colorbuffer loop stage.
 * This is used to implement GL_FRONT_AND_BACK rendering.
 */
struct quad_stage *sp_quad_bufloop_stage( struct softpipe_context *softpipe )
{
   struct quad_stage *stage = CALLOC_STRUCT(quad_stage);

   stage->softpipe = softpipe;
   stage->run = cbuf_loop_quad;

   return stage;
}