  Let $\mathcal{X}$ be a skew-symmetrizable cluster Poisson variety. The
cluster complex $\Delta^+(\mathcal{X})$ was introduced by Gross, Hacking, Keel
and Kontsevich. It codifies the theta functions on $\mathcal{X}$ that restrict
to a character of a seed torus. Every seed ${ \bf s}$ for $\mathcal{X}$
determines a fan realization $\Delta^+_{\bf s}(\mathcal{X})$ of
$\Delta^+(\mathcal{X})$. For every ${\bf s}$ we provide a simple and explicit
description of the cones of $\Delta^+_{{\bf s}}(\mathcal{X})$ and their facets
using ${\bf c}$-vectors. Moreover, we give formulas for the theta functions
parametrized by the integral points of $\Delta^+_{{ \bf s}}(\mathcal{X})$ in
terms of $F$-polynomials. In case $\mathcal{X}$ is skew-symmetric and the
quiver $Q$ associated to ${\bf s}$ is acyclic, we describe the normal vectors
of the supporting hyperplanes of the cones of $\Delta^+_{\bf s}(\mathcal{X})$
using ${\bf g}$-vectors of (non-necessarily rigid) objects in $\mathsf{K}^{\rm
b}(\text{proj} \; kQ)$.
