[Openflipper] How can i access a Vertex Property in a Shader

Hi, i want to write a shader, that sums up all values of a vertexproperty for all visible vertices and one with which i compute the color for each vertex using a vertexproperty. Are vertexproperties being pushed automatically into the pipeline or do i have to assign them manually? If necessary what needs to be done so that a shader can use a property and how can i access that property in my vertex shader. I already thought about a workaround, storing the property value for a vertex in a texture but is there a better way? Best Regards Sebastian von Hippel