[Feat] (MG_Impl): implement the query getters that write into a buffer object

glGetQueryBufferObjectiv and its three siblings were stubs. They are the ordinary query
getters with the destination changed from client memory to a buffer object, so everything
about the query itself - the name, whether it is still active, the parameter - is already
answered by the shared GetQueryObjectValue, including the errors it raises.

What was left is the destination: a negative offset is INVALID_VALUE, a name that is not a
buffer object is INVALID_OPERATION, and so is a write that would run past the end of the
buffer. The four differ only in the width they store, so they share one template.

direct_state_access.queries_errors passes on both backends, putting the group at 4 of 5.
queries_functional now reaches further into the test and ends in an unrelated InternalError
rather than a plain failure.

MobileGL/MG_Impl/GLImpl/Exporting/Definitions.cpp

@@ -1098,10 +1098,10 @@ DECLARE_GL_FUNCTION_HEAD(void, GetVertexArrayIndexed64iv, GLuint vaobj, GLuint i
 DECLARE_GL_FUNCTION_HEAD(void, CreateSamplers, GLsizei n, GLuint* samplers) DECLARE_GL_FUNCTION_END_NO_RETURN(void, CreateSamplers, n, samplers)
 DECLARE_GL_FUNCTION_STUB_HEAD(void, CreateProgramPipelines, GLsizei n, GLuint* pipelines) DECLARE_GL_FUNCTION_STUB_END_NO_RETURN(void, CreateProgramPipelines, n, pipelines)
 DECLARE_GL_FUNCTION_HEAD(void, CreateQueries, GLenum target, GLsizei n, GLuint* ids) DECLARE_GL_FUNCTION_END_NO_RETURN(void, CreateQueries, target, n, ids)
-DECLARE_GL_FUNCTION_STUB_HEAD(void, GetQueryBufferObjecti64v, GLuint id, GLuint buffer, GLenum pname, GLintptr offset) DECLARE_GL_FUNCTION_STUB_END_NO_RETURN(void, GetQueryBufferObjecti64v, id, buffer, pname, offset)
+DECLARE_GL_FUNCTION_HEAD(void, GetQueryBufferObjecti64v, GLuint id, GLuint buffer, GLenum pname, GLintptr offset) DECLARE_GL_FUNCTION_END_NO_RETURN(void, GetQueryBufferObjecti64v, id, buffer, pname, offset)
-DECLARE_GL_FUNCTION_STUB_HEAD(void, GetQueryBufferObjectiv, GLuint id, GLuint buffer, GLenum pname, GLintptr offset) DECLARE_GL_FUNCTION_STUB_END_NO_RETURN(void, GetQueryBufferObjectiv, id, buffer, pname, offset)
+DECLARE_GL_FUNCTION_HEAD(void, GetQueryBufferObjectiv, GLuint id, GLuint buffer, GLenum pname, GLintptr offset) DECLARE_GL_FUNCTION_END_NO_RETURN(void, GetQueryBufferObjectiv, id, buffer, pname, offset)
-DECLARE_GL_FUNCTION_STUB_HEAD(void, GetQueryBufferObjectui64v, GLuint id, GLuint buffer, GLenum pname, GLintptr offset) DECLARE_GL_FUNCTION_STUB_END_NO_RETURN(void, GetQueryBufferObjectui64v, id, buffer, pname, offset)
+DECLARE_GL_FUNCTION_HEAD(void, GetQueryBufferObjectui64v, GLuint id, GLuint buffer, GLenum pname, GLintptr offset) DECLARE_GL_FUNCTION_END_NO_RETURN(void, GetQueryBufferObjectui64v, id, buffer, pname, offset)
-DECLARE_GL_FUNCTION_STUB_HEAD(void, GetQueryBufferObjectuiv, GLuint id, GLuint buffer, GLenum pname, GLintptr offset) DECLARE_GL_FUNCTION_STUB_END_NO_RETURN(void, GetQueryBufferObjectuiv, id, buffer, pname, offset)
+DECLARE_GL_FUNCTION_HEAD(void, GetQueryBufferObjectuiv, GLuint id, GLuint buffer, GLenum pname, GLintptr offset) DECLARE_GL_FUNCTION_END_NO_RETURN(void, GetQueryBufferObjectuiv, id, buffer, pname, offset)
 DECLARE_GL_FUNCTION_HEAD(void, GetTextureSubImage, GLuint texture, GLint level, GLint xoffset, GLint yoffset, GLint zoffset, GLsizei width, GLsizei height, GLsizei depth, GLenum format, GLenum type, GLsizei bufSize, void* pixels) DECLARE_GL_FUNCTION_END_NO_RETURN(void, GetTextureSubImage, texture, level, xoffset, yoffset, zoffset, width, height, depth, format, type, bufSize, pixels)
 DECLARE_GL_FUNCTION_STUB_HEAD(void, GetCompressedTextureSubImage, GLuint texture, GLint level, GLint xoffset, GLint yoffset, GLint zoffset, GLsizei width, GLsizei height, GLsizei depth, GLsizei bufSize, void* pixels) DECLARE_GL_FUNCTION_STUB_END_NO_RETURN(void, GetCompressedTextureSubImage, texture, level, xoffset, yoffset, zoffset, width, height, depth, bufSize, pixels)
 DECLARE_GL_FUNCTION_STUB_HEAD(void, GetnCompressedTexImage, GLenum target, GLint lod, GLsizei bufSize, void* pixels) DECLARE_GL_FUNCTION_STUB_END_NO_RETURN(void, GetnCompressedTexImage, target, lod, bufSize, pixels)

MobileGL/MG_Impl/GLImpl/Query/GL_Query.cpp

@@ -62,6 +62,34 @@ namespace MobileGL::MG_Impl::GLImpl {
                                               MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", function, message));
         }
 
+        // The by-buffer query getters write the result into a buffer object instead of client
+        // memory. Everything about the query itself - the name, whether it is still active, the
+        // parameter - is checked by GetQueryObjectValue; what is left is the destination, so this
+        // resolves the buffer and confirms the write lands inside it (GL 4.6 core 4.2.1).
+        Bool ResolveQueryResultDestination(GLuint buffer, GLintptr offset, SizeT writeSize, const char* function,
+                                           SharedPtr<MG_State::GLState::BufferObject>& outBuffer) {
+            if (offset < 0) {
+                RecordQueryError(ErrorCode::InvalidValue, function, "Offset cannot be negative.");
+                return false;
+            }
+            if (!MG_State::pGLContext->ValidateBufferObject(buffer)) {
+                RecordQueryError(ErrorCode::InvalidOperation, function, "Buffer object does not exist.");
+                return false;
+            }
+            auto bufferObject = MG_State::pGLContext->GetBufferObject(buffer);
+            if (!bufferObject) {
+                RecordQueryError(ErrorCode::InvalidOperation, function, "Buffer object does not exist.");
+                return false;
+            }
+            if (static_cast<SizeT>(offset) + writeSize > bufferObject->GetSize()) {
+                RecordQueryError(ErrorCode::InvalidOperation, function,
+                                 "The query result does not fit in the buffer object at this offset.");
+                return false;
+            }
+            outBuffer = bufferObject;
+            return true;
+        }
+
         // Callers must hold g_queryObjectsMutex.
         QueryObject* FindQueryObjectLocked(GLuint id) {
             const auto it = g_liveQueryObjects.find(id);
@@ -160,6 +188,18 @@ namespace MobileGL::MG_Impl::GLImpl {
                 return false;
             }
         }
+
+        template <typename T>
+        void GetQueryBufferObject(GLuint id, GLuint buffer, GLenum pname, GLintptr offset, const char* function) {
+            SharedPtr<MG_State::GLState::BufferObject> bufferObject;
+            if (!ResolveQueryResultDestination(buffer, offset, sizeof(T), function, bufferObject)) return;
+
+            Uint64 value = 0;
+            if (!GetQueryObjectValue(id, pname, function, value)) return;
+
+            const T narrowed = static_cast<T>(value);
+            bufferObject->UploadSubData({const_cast<T*>(&narrowed), sizeof(T)}, static_cast<SizeT>(offset));
+        }
     } // namespace
 
     void GenQueries(GLsizei n, GLuint* ids) {
@@ -475,6 +515,22 @@ namespace MobileGL::MG_Impl::GLImpl {
         }
     }
 
+    void GetQueryBufferObjectiv(GLuint id, GLuint buffer, GLenum pname, GLintptr offset) {
+        GetQueryBufferObject<GLint>(id, buffer, pname, offset, __FUNCTION__);
+    }
+
+    void GetQueryBufferObjectuiv(GLuint id, GLuint buffer, GLenum pname, GLintptr offset) {
+        GetQueryBufferObject<GLuint>(id, buffer, pname, offset, __FUNCTION__);
+    }
+
+    void GetQueryBufferObjecti64v(GLuint id, GLuint buffer, GLenum pname, GLintptr offset) {
+        GetQueryBufferObject<GLint64>(id, buffer, pname, offset, __FUNCTION__);
+    }
+
+    void GetQueryBufferObjectui64v(GLuint id, GLuint buffer, GLenum pname, GLintptr offset) {
+        GetQueryBufferObject<GLuint64>(id, buffer, pname, offset, __FUNCTION__);
+    }
+
     void GetQueryObjectiv(GLuint id, GLenum pname, GLint* params) {
         Uint64 value = 0;
         if (!GetQueryObjectValue(id, pname, __FUNCTION__, value) || !params) {

MobileGL/MG_Impl/GLImpl/Query/GL_Query.h

@@ -24,5 +24,9 @@ namespace MobileGL::MG_Impl::GLImpl {
     void GetQueryObjectuiv(GLuint id, GLenum pname, GLuint* params);
     void GetQueryObjecti64v(GLuint id, GLenum pname, GLint64* params);
     void GetQueryObjectui64v(GLuint id, GLenum pname, GLuint64* params);
+    void GetQueryBufferObjectiv(GLuint id, GLuint buffer, GLenum pname, GLintptr offset);
+    void GetQueryBufferObjectuiv(GLuint id, GLuint buffer, GLenum pname, GLintptr offset);
+    void GetQueryBufferObjecti64v(GLuint id, GLuint buffer, GLenum pname, GLintptr offset);
+    void GetQueryBufferObjectui64v(GLuint id, GLuint buffer, GLenum pname, GLintptr offset);
     void QueryCounter(GLuint id, GLenum target);
 } // namespace MobileGL::MG_Impl::GLImpl