1WGL_ATI_pixel_format_float 2http://oss.sgi.com/projects/ogl-sample/registry/ATI/pixel_format_float.txt 3 WGL_TYPE_RGBA_FLOAT_ATI 0x21A0 4 GL_RGBA_FLOAT_MODE_ATI 0x8820 5 GL_COLOR_CLEAR_UNCLAMPED_VALUE_ATI 0x8835 6