GL: new "intel-windows-broken-dsa-integer-vertex-attributes" workaround.

doc/changelog.dox

@@ -91,6 +91,9 @@ See also:
         fixing @ref GL::Framebuffer::clearColor()
     -   @cpp "intel-windows-broken-dsa-indexed-queries" @ce fixing
         @ref GL::PrimitiveQuery::begin(UnsignedInt)
+    -   @cpp "intel-windows-broken-dsa-integer-vertex-attributes" @ce fixing
+        @ref GL::Mesh::addVertexBuffer() with @ref Magnum::Short "Short"
+        attributes
 -   New `--magnum-gpu-validation` @ref GL-Context-command-line "command-line option"
     and a corresponding environment variable to conveniently enable
     @gl_extension{KHR,debug} debug output

src/Magnum/GL/Implementation/MeshState.cpp

@@ -57,8 +57,19 @@ MeshState::MeshState(Context& context, ContextState& contextState, std::vector<s
         if(context.isExtensionSupported<Extensions::ARB::direct_state_access>()) {
             extensions.emplace_back(Extensions::ARB::direct_state_access::string());
 
+            /* Intel Windows drivers are ... special */
+            #ifdef CORRADE_TARGET_WINDOWS
+            if((context.detectedDriver() & Context::DetectedDriver::IntelWindows) &&
+               !context.isDriverWorkaroundDisabled("intel-windows-broken-dsa-integer-vertex-attributes"))
+            {
+                attributePointerImplementation = &Mesh::attributePointerImplementationVAODSAIntelWindows;
+            } else
+            #endif
+            {
+                attributePointerImplementation = &Mesh::attributePointerImplementationVAODSA;
+            }
+
             createImplementation = &Mesh::createImplementationVAODSA;
-            attributePointerImplementation = &Mesh::attributePointerImplementationVAODSA;
             bindIndexBufferImplementation = &Mesh::bindIndexBufferImplementationVAODSA;
         } else
         #endif

src/Magnum/GL/Implementation/driverSpecific.cpp

@@ -239,6 +239,13 @@ namespace {
            glBeginQueryIndexed(). Using the non-DSA glGenQueries() instead
            makes it work properly. See TransformFeedbackGLTest for a test. */
         "intel-windows-broken-dsa-indexed-queries",
+
+        /* DSA-ified "vertex layout" glVertexArrayAttribIFormat() is broken
+           when passing shorts instead of full 32bit ints. Using the old-style
+           glVertexAttribIPointer() works correctly. No idea if the non-DSA
+           glVertexAttribIFormat() works or not. A test that triggers this
+           issue is in MeshGLTest::addVertexBufferIntWithShort(). */
+        "intel-windows-broken-dsa-integer-vertex-attributes",
         #endif
 
         #ifndef MAGNUM_TARGET_GLES

src/Magnum/GL/Mesh.cpp

@@ -700,6 +700,17 @@ void Mesh::attributePointerImplementationVAODSA(AttributeLayout&& attribute) {
     if(attribute.divisor)
         (this->*Context::current().state().mesh->vertexAttribDivisorImplementation)(attribute.location, attribute.divisor);
 }
+
+#ifdef CORRADE_TARGET_WINDOWS
+void Mesh::attributePointerImplementationVAODSAIntelWindows(AttributeLayout&& attribute) {
+    /* See the "intel-windows-broken-dsa-integer-vertex-attributes" workaround
+       for more information. */
+    if(attribute.kind == DynamicAttribute::Kind::Integral)
+        return attributePointerImplementationVAO(std::move(attribute));
+    else
+        return attributePointerImplementationVAODSA(std::move(attribute));
+}
+#endif
 #endif
 
 void Mesh::vertexAttribPointer(AttributeLayout& attribute) {

src/Magnum/GL/Mesh.h

@@ -1112,6 +1112,9 @@ class MAGNUM_GL_EXPORT Mesh: public AbstractObject {
         void MAGNUM_GL_LOCAL attributePointerImplementationVAO(AttributeLayout&& attribute);
         #ifndef MAGNUM_TARGET_GLES
         void MAGNUM_GL_LOCAL attributePointerImplementationVAODSA(AttributeLayout&& attribute);
+        #ifdef CORRADE_TARGET_WINDOWS
+        void MAGNUM_GL_LOCAL attributePointerImplementationVAODSAIntelWindows(AttributeLayout&& attribute);
+        #endif
         #endif
         void MAGNUM_GL_LOCAL vertexAttribPointer(AttributeLayout& attribute);