#version 450
#extension GL_EXT_descriptor_heap: require

struct Data
{
    mat4 m;
    float f;
};

layout(descriptor_heap) uniform U { Data inputData;    }  ubo[];
layout(descriptor_heap)  buffer O { Data outputData[]; } ssbo[];

void main()
{
    Data data = ubo[1].inputData;
    data.f += 1.0;
    ssbo[2].outputData[3] = data;
}