Add some support for 16 and 32 bits per color channel.

panda/src/glstuff/glGraphicsStateGuardian_src.cxx

@@ -4817,6 +4817,8 @@ get_external_image_format(Texture *tex) const {
   case Texture::F_rgba5:
   case Texture::F_rgba8:
   case Texture::F_rgba12:
+  case Texture::F_rgba16:
+  case Texture::F_rgba32:
     return _supports_bgr ? GL_BGRA : GL_RGBA;
   case Texture::F_luminance:
     return GL_LUMINANCE;
@@ -4970,6 +4972,11 @@ get_internal_image_format(Texture *tex) const {
   case Texture::F_rgba12:
     return GL_RGBA12;
 
+  case Texture::F_rgba16:
+    return GL_RGBA16F_ARB;
+  case Texture::F_rgba32:
+    return GL_RGBA32F_ARB;
+
   case Texture::F_rgb:
     return GL_RGB;
   case Texture::F_rgb5: