GL: add *Texture::target().

Useful when interacting with raw GL code.

doc/changelog.dox

@@ -60,6 +60,8 @@ See also:
     @webgl_extension{WEBGL,multi_draw_instanced_base_vertex_base_instance}
     extensions, however there's no Emscripten entrypoints for those yet which
     means these can'be implemented right now.
+-   Added a @ref GL::AbstractTexture::target() getter to simplify interaction
+    with raw GL code
 
 @subsubsection changelog-latest-new-math Math library
 

src/Magnum/GL/AbstractTexture.h

@@ -332,6 +332,12 @@ class MAGNUM_GL_EXPORT AbstractTexture: public AbstractObject {
         /** @brief OpenGL texture ID */
         GLuint id() const { return _id; }
 
+        /**
+         * @brief OpenGL texture target
+         * @m_since_latest
+         */
+        GLenum target() const { return _target; }
+
         /**
          * @brief Release OpenGL object
          *

src/Magnum/GL/Test/AbstractTextureGLTest.cpp

@@ -96,6 +96,7 @@ void AbstractTextureGLTest::construct() {
 
         MAGNUM_VERIFY_NO_GL_ERROR();
         CORRADE_VERIFY(texture.id() > 0);
+        CORRADE_COMPARE(texture.target(), GL_TEXTURE_2D);
     }
 
     MAGNUM_VERIFY_NO_GL_ERROR();