public int SetVertexAttributes(VertexBuffer[] vertexBuffers, int previousAttributesBound)
        {
            int totalSlotsBound = 0;

            for (int i = 0; i < VBLayoutsBySlot.Length; i++)
            {
                OpenGLMaterialVertexInput input = VBLayoutsBySlot[i];
                ((OpenGLVertexBuffer)vertexBuffers[i]).Apply();
                for (int slot = 0; slot < input.Elements.Length; slot++)
                {
                    OpenGLMaterialVertexInputElement element = input.Elements[slot];
                    int actualSlot = totalSlotsBound + slot;
                    GL.EnableVertexAttribArray(actualSlot);
                    GL.VertexAttribPointer(actualSlot, element.ElementCount, element.Type, element.Normalized, input.VertexSizeInBytes, element.Offset);
                    GL.VertexAttribDivisor(actualSlot, element.InstanceStepRate);
                }

                totalSlotsBound += input.Elements.Length;
            }

            for (int extraSlot = totalSlotsBound; extraSlot < previousAttributesBound; extraSlot++)
            {
                GL.DisableVertexAttribArray(extraSlot);
            }

            return(totalSlotsBound);
        }
        public int SetVertexAttributes(int vertexBufferSlot, OpenGLVertexBuffer vb, int previousAttributesBound)
        {
            // TODO: Related to OpenGLRenderContext.PlatformSetVertexBuffer()
            // These attributes should be lazily set on a draw call or something.
            if (vertexBufferSlot <= VBLayoutsBySlot.Length)
            {
                return(previousAttributesBound);
            }

            int baseSlot = GetSlotBaseIndex(vertexBufferSlot);
            OpenGLMaterialVertexInput input = VBLayoutsBySlot[vertexBufferSlot];

            vb.Apply();
            for (int i = 0; i < input.Elements.Length; i++)
            {
                OpenGLMaterialVertexInputElement element = input.Elements[i];
                int slot = baseSlot + i;
                GL.EnableVertexAttribArray(slot);
                GL.VertexAttribPointer(slot, element.ElementCount, element.Type, element.Normalized, input.VertexSizeInBytes, element.Offset);
            }
            for (int extraSlot = input.Elements.Length; extraSlot < previousAttributesBound; extraSlot++)
            {
                GL.DisableVertexAttribArray(extraSlot);
            }

            return(input.Elements.Length);
        }