mixtures.h

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#pragma once

#include <cugar/sampling/random.h>
#include <cugar/linalg/vector.h>
#include <cugar/linalg/matrix.h>

namespace cugar {

template <typename TDistribution, uint32 NCOMP>
struct Mixture
{
    typedef TDistribution   distribution_type;

    static const uint32     NUM_COMPONENTS = NCOMP;


    CUGAR_HOST_DEVICE Mixture()
    {
        // initialize the weights
        for (uint32 i = 0; i < NUM_COMPONENTS; ++i)
            weights[i] = 1.0f / NUM_COMPONENTS;
    }

    CUGAR_HOST_DEVICE 
    uint32 size() const { return NCOMP; }

    CUGAR_HOST_DEVICE float density(const Vector2f x) const
    {
        float p = 0.0f;
        for (uint32 i = 0; i < NCOMP; ++i)
            p += weights[i] * comps[i].density(x);
        return p;
    }

    CUGAR_HOST_DEVICE float density(const uint32 i, const Vector2f x) const
    {
        return comps[i].density(x);
    }

    CUGAR_HOST_DEVICE const distribution_type& component(const uint32 i) const { return comps[i]; }

    CUGAR_HOST_DEVICE distribution_type& component(const uint32 i) { return comps[i]; }

    CUGAR_HOST_DEVICE void set_component(const uint32 i, const distribution_type& c, const float w) { comps[i] = c; weights[i] = w; }

    CUGAR_HOST_DEVICE void set_component(const uint32 i, const distribution_type& c) { comps[i] = c; }

    CUGAR_HOST_DEVICE float weight(const uint32 i) const { return weights[i]; }

    CUGAR_HOST_DEVICE void set_weight(const uint32 i, const float w) { weights[i] = w; }

private:
    TDistribution   comps[NCOMP];
    float           weights[NCOMP];
};

} // namespace cugar