Troubles With Dynamic Memory

Nick

Sage

Posts: 1,066
Joined: 2004.07

Post: #1

Sep 7, 2005 — 08:33 PM

So I decided to start learning pointers and dynamic memory management so I tried my hand at writing a little particle solver that would just let a bunch of circles fall from the top-center of the screen and, if they fell off any direction, they'd reset to their origin. For some reason, though, when I run the program, I don't even see any of the particles. Is it involving the dynamic memory or is another simple error to blame?

Here's the header:

Code:

/*

 *  ParticleSolver.h

 *

 *  Copyright 2005 SimReality Games. All rights reserved.

 *

 */

#ifndef __PARTICLESOLVER_H

#define __PARTICLESOLVER_H

#include <OpenGL/OpenGL.h>

#include <OpenGL/gl.h>

#include "Particle.h"

class ParticleSolver

{

public:

    ParticleSolver();

    ~ParticleSolver();

    ParticleSolver(int numParticles);

    void Resize(int numParticles);

    void UpdateParticles(float frameRate);

    void DrawParticles();

    Particle *particles;

    int numberOfParticles;

};

#endif

And the .cpp:

Code:

/*

 *  ParticleSolver.cpp

 *

 *  Copyright 2005 SimReality Games. All rights reserved.

 *

 */

#include "ParticleSolver.h"

extern int screenWidth, screenHeight;

extern GLint myList;

ParticleSolver::ParticleSolver()

{

    particles = new Particle();

    numberOfParticles = 0;

}

ParticleSolver::~ParticleSolver()

{

    delete[] particles;

}

ParticleSolver::ParticleSolver(int numParticles)

{

    particles = new Particle[numParticles];

    numberOfParticles = numParticles;

}

void ParticleSolver::Resize(int numParticles)

{   

    Particle *tempStorage = particles;

    particles = new Particle[numParticles];

    int workingSize = (numParticles < numberOfParticles) ? numParticles : numberOfParticles;

    for(int i = 0; i < workingSize; i++)

        particles[i].CopyData(tempStorage[i]);

    delete[] tempStorage;

}

void ParticleSolver::UpdateParticles(float frameRate)

{

    for(int i = 0; i < numberOfParticles; i++)

    {

        particles[i].position.x += particles[i].velocity.x;

        particles[i].position.y += particles[i].velocity.y;

        particles[i].position.z += particles[i].velocity.z;

        if(particles[i].position.y > screenHeight ||

           particles[i].position.x < 0 ||

           particles[i].position.x > screenWidth)

        {

            particles[i].position.y = 0;

            particles[i].position.x = screenWidth / 2;

        }

    }

}

void ParticleSolver::DrawParticles()

{

    for(int i = 0; i < numberOfParticles; i++)

    {

        glPushMatrix();

        {

            glScalef(10,10,10);

            glTranslatef(particles[i].position.x,

                         particles[i].position.y,

                         particles[i].position.z);

            glCallList(myList);

        }

        glPopMatrix();

    }

}

Nick

Sage

Posts: 1,066
Joined: 2004.07

Post: #2

Sep 7, 2005 — 08:56 PM

Ok. Thanks to akb825, I found out that I should have my glScale and glTranslate functions called in the opposite order (translate, then scale). Now if anyone reads this and has a similar problem, they can fix it.

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