SpotLight.cpp

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#include "SpotLight.h"
#include "ngl/VBOPrimitives.h"
#include "ngl/Vector.h"
#include "ngl/Matrix.h"
#include "NGLMath.h"
#include "ngl/ShaderManager.h"
#include "ngl/Camera.h"

#include "math.h"

#include <cstring>

SpotLight::SpotLight(const ngl::Vector &_position, const ngl::Vector &_target, const float &_distance, const float &_angle, const ngl::Vector &_col, const ngl::Vector &_up)
{
    this->set(_position,_target,_distance,_angle,_col,_up);
}

SpotLight::~SpotLight(){}

bool SpotLight::collidesWithSphere(const ngl::Vector &_pos, const float &_rad)
{
    float radius = m_directionDistance.m_w * 0.5;

    ngl::Vector centre = ngl::Vector(m_directionDistance.m_x, m_directionDistance.m_y, m_directionDistance.m_z) * (m_directionDistance.m_w * 0.5);

    ngl::Vector length = centre-_pos;
    float lengthSq = length.lengthSquared();

    float radiiSq = (radius*radius)*1.5 /*scale up to avoid nasty culling */ + (_rad*_rad);

    return lengthSq < radiiSq;
}

void SpotLight::draw(const std::string &_vaoName, const std::string &_shader)
{
    ngl::ShaderManager *shader = ngl::ShaderManager::instance();

    (*shader)[_shader]->use();

    shader->setShaderParamFromMatrix(_shader, "u_ModelMatrix", m_world);
    shader->setShaderParamFromVector(_shader, "a_PositionAngle", m_positionAngle);
    shader->setShaderParamFromVector(_shader, "a_DirectionDistance", m_directionDistance);
    shader->setShaderParamFromVector(_shader, "a_Colour", m_colour);

    ngl::VBOPrimitives *prim = ngl::VBOPrimitives::instance();
    prim->draw(_vaoName);
}

void SpotLight::set(
        const ngl::Vector &_position,
        const ngl::Vector &_target,
        const float &_distance,
        const float &_angle,
        const ngl::Vector &_col,
        const ngl::Vector &_up
        )
{
    const float xyscale = _distance*sinf( ( _angle*.5)*ngl::PI/180 ) * 1.1f; // Scaling up to avoid hard edges eating the light

    ngl::Matrix scale, invView, trans;

    scale.scale(xyscale,xyscale,_distance);

    m_matrixCam = ngl::Camera(_position, _target, _up, ngl::PERSPECTIVE);

    m_lightView = Lookat(_position,_target,_up);
    invView = Inverse(m_lightView);
    
    //magic number to get ngl cone into position
    trans.translate(0,0,-1);

    m_world =  invView * scale * trans;

    ngl::Vector direction = _target-_position;
    direction.normalize();

    m_positionAngle = _position;
    m_positionAngle.m_w=cos( ( _angle*.5)*ngl::PI/180 );
    m_directionDistance = direction;
    m_directionDistance.m_w=_distance;
    m_colour = _col;
}