Panda3D

specbuf.cxx

00001 #include "zgl.h"
00002 #include <math.h>
00003 #include <stdlib.h>
00004 
00005 static void calc_buf(GLSpecBuf *buf, const PN_stdfloat shininess)
00006 {
00007   int i;
00008   PN_stdfloat val, inc;
00009   val = 0.0f;
00010   inc = 1.0f/SPECULAR_BUFFER_SIZE;
00011   for (i = 0; i <= SPECULAR_BUFFER_SIZE; i++) {
00012     buf->buf[i] = pow(val, shininess);
00013     val += inc;
00014   }
00015 }
00016 
00017 GLSpecBuf *
00018 specbuf_get_buffer(GLContext *c, const int shininess_i, 
00019                    const PN_stdfloat shininess)
00020 {
00021   GLSpecBuf *found, *oldest;
00022   found = oldest = c->specbuf_first;
00023   while (found && found->shininess_i != shininess_i) {
00024     if (found->last_used < oldest->last_used) {
00025       oldest = found;
00026     }
00027     found = found->next; 
00028   }
00029   if (found) { /* hey, found one! */
00030     found->last_used = c->specbuf_used_counter++;
00031     return found;
00032   }
00033   if (oldest == NULL || c->specbuf_num_buffers < MAX_SPECULAR_BUFFERS) {
00034     /* create new buffer */
00035     GLSpecBuf *buf = (GLSpecBuf *)gl_malloc(sizeof(GLSpecBuf));
00036     if (!buf) gl_fatal_error("could not allocate specular buffer");
00037     c->specbuf_num_buffers++;
00038     buf->next = c->specbuf_first;
00039     c->specbuf_first = buf;
00040     buf->last_used = c->specbuf_used_counter++;
00041     buf->shininess_i = shininess_i;
00042     calc_buf(buf, shininess);
00043     return buf;     
00044   }
00045   /* overwrite the lru buffer */
00046   oldest->shininess_i = shininess_i;
00047   oldest->last_used = c->specbuf_used_counter++;
00048   calc_buf(oldest, shininess);
00049   return oldest;
00050 }
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