+ if(i>=4)
+ throw out_of_range("TexUnit::get_texgen");
+ return texgen[i];
+}
+
+void TexUnit::bind()
+{
+ if(cur_unit!=this && (cur_unit || index))
+ glActiveTexture(GL_TEXTURE0+index);
+ cur_unit = this;
+}
+
+unsigned TexUnit::get_n_units()
+{
+ static int count = -1;
+ if(count<0)
+ {
+ if(ARB_vertex_shader)
+ glGetIntegerv(GL_MAX_TEXTURE_IMAGE_UNITS, &count);
+ else if(ARB_multitexture)
+ glGetIntegerv(GL_MAX_TEXTURE_UNITS, &count);
+ else
+ count = 1;
+ }
+ return count;
+}
+
+TexUnit &TexUnit::get_unit(unsigned n)
+{
+ if(n>0)
+ static Require _req(ARB_multitexture);
+ if(n>=get_n_units())
+ throw out_of_range("TexUnit::get_unit");
+