Use a single index array

There's no point in clearing the index array because it is always the
same sequence of indices regardless of the vertices. Instead it is
just added to when there are more vertices than ever before.

clutter/cogl/gl/cogl-texture.c

@@ -1918,9 +1918,41 @@ _cogl_texture_flush_vertices (void)
 
   if (ctx->texture_vertices->len > 0)
     {
+      int needed_indices;
       CoglTextureGLVertex *p
         = (CoglTextureGLVertex *) ctx->texture_vertices->data;
 
+      /* The indices are always the same sequence regardless of the
+         vertices so we only need to change it if there are more
+         vertices than ever before */
+      needed_indices = ctx->texture_vertices->len / 4 * 6;
+      if (needed_indices > ctx->texture_indices->len)
+        {
+          int old_len = ctx->texture_indices->len;
+          int vert_num = old_len / 6 * 4;
+          int i;
+          GLushort *q;
+
+          /* Add two triangles for each quad to the list of
+             indices. That makes six new indices but two of the
+             vertices in the triangles are shared. */
+          g_array_set_size (ctx->texture_indices, needed_indices);
+          q = &g_array_index (ctx->texture_indices, GLushort, old_len);
+
+          for (i = old_len;
+               i < ctx->texture_indices->len;
+               i += 6, vert_num += 4)
+            {
+              *(q++) = vert_num + 0;
+              *(q++) = vert_num + 1;
+              *(q++) = vert_num + 3;
+
+              *(q++) = vert_num + 1;
+              *(q++) = vert_num + 2;
+              *(q++) = vert_num + 3;
+            }
+        }
+
       GE( glVertexPointer (2, GL_FLOAT,
                            sizeof (CoglTextureGLVertex), p->v ) );
       GE( glTexCoordPointer (2, GL_FLOAT,
@@ -1929,12 +1961,11 @@ _cogl_texture_flush_vertices (void)
       GE( glBindTexture (ctx->texture_target, ctx->texture_current) );
       GE( ctx->pf_glDrawRangeElements (GL_TRIANGLES,
                                        0, ctx->texture_vertices->len - 1,
-                                       ctx->texture_indices->len,
+                                       needed_indices,
                                        GL_UNSIGNED_SHORT,
                                        ctx->texture_indices->data) );
 
       g_array_set_size (ctx->texture_vertices, 0);
-      g_array_set_size (ctx->texture_indices, 0);
     }
 }
 
@@ -1946,7 +1977,6 @@ _cogl_texture_add_quad_vertices (GLfloat x1, GLfloat y1,
 {
   CoglTextureGLVertex *p;
   GLushort first_vert;
-  GLushort *q;
 
   _COGL_GET_CONTEXT (ctx, NO_RETVAL);
 
@@ -1968,21 +1998,6 @@ _cogl_texture_add_quad_vertices (GLfloat x1, GLfloat y1,
   p->v[0] = x2;  p->v[1] = y1;
   p->t[0] = tx2; p->t[1] = ty1;
   p++;
-
-  /* Add two triangles to the list of indices. That makes six new
-     indices but two of the vertices in the triangles are shared. */
-  g_array_set_size (ctx->texture_indices,
-                    ctx->texture_indices->len + 6);
-  q = &g_array_index (ctx->texture_indices, GLushort,
-                      ctx->texture_indices->len - 6);
-
-  *(q++) = first_vert + 0;
-  *(q++) = first_vert + 1;
-  *(q++) = first_vert + 3;
-
-  *(q++) = first_vert + 1;
-  *(q++) = first_vert + 2;
-  *(q++) = first_vert + 3;
 }
 
 static void

clutter/cogl/gles/cogl-texture.c

@@ -2054,9 +2054,41 @@ _cogl_texture_flush_vertices (void)
 
   if (ctx->texture_vertices->len > 0)
     {
+      int needed_indices;
       CoglTextureGLVertex *p
         = (CoglTextureGLVertex *) ctx->texture_vertices->data;
 
+      /* The indices are always the same sequence regardless of the
+         vertices so we only need to change it if there are more
+         vertices than ever before */
+      needed_indices = ctx->texture_vertices->len / 4 * 6;
+      if (needed_indices > ctx->texture_indices->len)
+        {
+          int old_len = ctx->texture_indices->len;
+          int vert_num = old_len / 6 * 4;
+          int i;
+          GLushort *q;
+
+          /* Add two triangles for each quad to the list of
+             indices. That makes six new indices but two of the
+             vertices in the triangles are shared. */
+          g_array_set_size (ctx->texture_indices, needed_indices);
+          q = &g_array_index (ctx->texture_indices, GLushort, old_len);
+
+          for (i = old_len;
+               i < ctx->texture_indices->len;
+               i += 6, vert_num += 4)
+            {
+              *(q++) = vert_num + 0;
+              *(q++) = vert_num + 1;
+              *(q++) = vert_num + 3;
+
+              *(q++) = vert_num + 1;
+              *(q++) = vert_num + 2;
+              *(q++) = vert_num + 3;
+            }
+        }
+
       GE( glVertexPointer (2, GL_FLOAT,
                            sizeof (CoglTextureGLVertex), p->v ) );
       GE( glTexCoordPointer (2, GL_FLOAT,
@@ -2064,12 +2096,11 @@ _cogl_texture_flush_vertices (void)
 
       GE( glBindTexture (ctx->texture_target, ctx->texture_current) );
       GE( glDrawElements (GL_TRIANGLES,
-                          ctx->texture_indices->len,
+                          needed_indices,
                           GL_UNSIGNED_SHORT,
                           ctx->texture_indices->data) );
 
       g_array_set_size (ctx->texture_vertices, 0);
-      g_array_set_size (ctx->texture_indices, 0);
     }
 }
 
@@ -2081,7 +2112,6 @@ _cogl_texture_add_quad_vertices (GLfloat x1, GLfloat y1,
 {
   CoglTextureGLVertex *p;
   GLushort first_vert;
-  GLushort *q;
 
   _COGL_GET_CONTEXT (ctx, NO_RETVAL);
 
@@ -2103,21 +2133,6 @@ _cogl_texture_add_quad_vertices (GLfloat x1, GLfloat y1,
   p->v[0] = x2;  p->v[1] = y1;
   p->t[0] = tx2; p->t[1] = ty1;
   p++;
-
-  /* Add two triangles to the list of indices. That makes six new
-     indices but two of the vertices in the triangles are shared. */
-  g_array_set_size (ctx->texture_indices,
-                    ctx->texture_indices->len + 6);
-  q = &g_array_index (ctx->texture_indices, GLushort,
-                      ctx->texture_indices->len - 6);
-
-  *(q++) = first_vert + 0;
-  *(q++) = first_vert + 1;
-  *(q++) = first_vert + 3;
-
-  *(q++) = first_vert + 1;
-  *(q++) = first_vert + 2;
-  *(q++) = first_vert + 3;
 }
 
 static void