GL: add Framebuffer::InvalidationAttachment::DepthStencil

Not available on GLES2, similar to BufferAttachment but with the added
constraint that WebGL1 doesn't support invalidating attachments at all.

Not adding this for DefaultFramebuffer since that takes different target
values, and GL_DEPTH_STENCIL is not one of them.

src/Magnum/GL/Framebuffer.cpp

@@ -73,6 +73,9 @@ const Framebuffer::BufferAttachment Framebuffer::BufferAttachment::DepthStencil
 #if !(defined(MAGNUM_TARGET_WEBGL) && defined(MAGNUM_TARGET_GLES2))
 const Framebuffer::InvalidationAttachment Framebuffer::InvalidationAttachment::Depth = Framebuffer::InvalidationAttachment(GL_DEPTH_ATTACHMENT);
 const Framebuffer::InvalidationAttachment Framebuffer::InvalidationAttachment::Stencil = Framebuffer::InvalidationAttachment(GL_STENCIL_ATTACHMENT);
+#ifndef MAGNUM_TARGET_GLES2
+const Framebuffer::InvalidationAttachment Framebuffer::InvalidationAttachment::DepthStencil = Framebuffer::InvalidationAttachment(GL_DEPTH_STENCIL_ATTACHMENT);
+#endif
 #endif
 
 Int Framebuffer::maxColorAttachments() {

src/Magnum/GL/Framebuffer.h

@@ -256,6 +256,21 @@ class MAGNUM_GL_EXPORT Framebuffer: public AbstractFramebuffer, public AbstractO
                  */
                 static const InvalidationAttachment Stencil;
 
+                #ifndef MAGNUM_TARGET_GLES2
+                /**
+                 * @brief Invalidate both depth and stencil buffer
+                 * @m_since_latest
+                 *
+                 * @m_keywords{GL_DEPTH_STENCIL_ATTACHMENT}
+                 * @requires_gles30 Combined depth and stencil attachment is
+                 *      not available in OpenGL ES 2.0. Invalidate both
+                 *      @ref InvalidationAttachment::Depth and
+                 *      @ref InvalidationAttachment::Stencil instead.
+                 * @todo Support this in ES2 (invalidate both depth and stencil internally)
+                 */
+                static const InvalidationAttachment DepthStencil;
+                #endif
+
                 /** @brief Invalidate color buffer */
                 constexpr /*implicit*/ InvalidationAttachment(Framebuffer::ColorAttachment attachment): attachment(GLenum(attachment)) {}
 

src/Magnum/GL/Test/FramebufferGLTest.cpp

@@ -126,6 +126,9 @@ struct FramebufferGLTest: OpenGLTester {
     void invalidate();
     #endif
     #ifndef MAGNUM_TARGET_GLES2
+    void invalidateCombinedDepthStencil();
+    #endif
+    #ifndef MAGNUM_TARGET_GLES2
     void invalidateSub();
     #endif
     void read();
@@ -269,6 +272,9 @@ FramebufferGLTest::FramebufferGLTest() {
               &FramebufferGLTest::invalidate,
               #endif
               #ifndef MAGNUM_TARGET_GLES2
+              &FramebufferGLTest::invalidateCombinedDepthStencil,
+              #endif
+              #ifndef MAGNUM_TARGET_GLES2
               &FramebufferGLTest::invalidateSub,
               #endif
               &FramebufferGLTest::read,
@@ -1400,6 +1406,40 @@ void FramebufferGLTest::invalidate() {
     framebuffer.invalidate({Framebuffer::InvalidationAttachment::Depth, Framebuffer::ColorAttachment(0)});
 
     MAGNUM_VERIFY_NO_GL_ERROR();
+
+    #ifndef MAGNUM_TARGET_GLES2
+    /* Invalidating combined bits should work as well even if there's just stencil alone */
+    framebuffer.invalidate({Framebuffer::InvalidationAttachment::DepthStencil});
+
+    MAGNUM_VERIFY_NO_GL_ERROR();
+    #endif
+}
+#endif
+
+#ifndef MAGNUM_TARGET_GLES2
+void FramebufferGLTest::invalidateCombinedDepthStencil() {
+    #ifndef MAGNUM_TARGET_GLES
+    if(!Context::current().isExtensionSupported<Extensions::ARB::framebuffer_object>())
+        CORRADE_SKIP(Extensions::ARB::framebuffer_object::string() << "is not supported.");
+    #endif
+
+    Renderbuffer depthStencil;
+    depthStencil.setStorage(RenderbufferFormat::Depth24Stencil8, Vector2i(128));
+
+    Framebuffer framebuffer({{}, Vector2i(128)});
+    framebuffer.attachRenderbuffer(Framebuffer::BufferAttachment::DepthStencil, depthStencil);
+
+    MAGNUM_VERIFY_NO_GL_ERROR();
+
+    framebuffer.invalidate({Framebuffer::InvalidationAttachment::DepthStencil});
+
+    MAGNUM_VERIFY_NO_GL_ERROR();
+
+    /* Invalidating separate bits should work as well */
+    framebuffer.invalidate({Framebuffer::InvalidationAttachment::Depth,
+                            Framebuffer::InvalidationAttachment::Stencil});
+
+    MAGNUM_VERIFY_NO_GL_ERROR();
 }
 #endif