TrackballCamera.cpp

# include"TrackballCamera.h"

namespace DirectGraphicalModels { namespace vis 
{
    void CTrackballCamera::reset(void)
    {
        m_theta             = m_initTheta;
        m_phi               = m_initPhi;
        m_radius            = m_initRadius;
        m_up                = m_phi >= 0 ? 1.0f : -1.0f;
        m_target            = glm::vec3(0);
        m_viewNeedsUpdate   = true;
    }
    
    glm::mat4 CTrackballCamera::getViewMatrix(void)
    {
        if (m_viewNeedsUpdate) {
            updateViewMatrix();
            m_viewNeedsUpdate = false;
        }
        return m_view;
    }

    // ====================================== Potected ======================================
    void CTrackballCamera::rotate(float dTheta, float dPhi)
    {
        m_viewNeedsUpdate = true;

        // Update theta and phi
        if (m_up > 0.0f) m_theta += dTheta;
        else             m_theta -= dTheta;
        m_phi += dPhi;

        // Keep phi within -2Pi to +2Pi for easy 'up' comparison 
        if (m_phi > 2 * glm::pi<float>())   m_phi -= 2 * glm::pi<float>();
        else if (m_phi < -2 * glm::pi<float>()) m_phi += 2 * glm::pi<float>();

        // If phi is between 0 to Pi or -Pi to -2Pi, make 'up' be positive Y, other wise make it negative Y 
        if ((m_phi > 0 && m_phi < glm::pi<float>()) || (m_phi < -glm::pi<float>() && m_phi > -2 * glm::pi<float>())) m_up = 1.0f;
        else                                                                                                         m_up = -1.0f;
    }

    void CTrackballCamera::zoom(float dRadius)
    {
        m_viewNeedsUpdate = true;
        m_radius -= dRadius;
        if (m_radius <= 0.1f) m_radius = 0.1f;
    }

    void CTrackballCamera::pan(float dx, float dy)
    {
        m_viewNeedsUpdate = true;

        glm::vec3 look = glm::normalize(getCameraOrintation());
        glm::vec3 worldUp = glm::vec3(0.0f, m_up, 0.0f);
        glm::vec3 right = glm::cross(look, worldUp);
        glm::vec3 up = glm::cross(look, right);

        m_target += (right * dx) + (up * dy);
    }

} }