[patrik]

You could make a script like this and run before the cmake (or set the envs manually).

#!/bin/bash

QT_BASE_DIR=/path/to/qt512
export QTDIR=$QT_BASE_DIR
export PATH=$QT_BASE_DIR/bin:$PATH

if [[ $(uname -m) == "x86_64" ]]; then
  export LD_LIBRARY_PATH=$QT_BASE_DIR/lib/x86_64-linux-gnu:$QT_BASE_DIR/lib:$LD_LIBRARY_PATH
else
  export LD_LIBRARY_PATH=$QT_BASE_DIR/lib/i386-linux-gnu:$QT_BASE_DIR/lib:$LD_LIBRARY_PATH
fi

export PKG_CONFIG_PATH=$QT_BASE_DIR/lib/pkgconfig:$PKG_CONFIG_PATH