• Announcements

    • khawk

      Download the Game Design and Indie Game Marketing Freebook   07/19/17

      GameDev.net and CRC Press have teamed up to bring a free ebook of content curated from top titles published by CRC Press. The freebook, Practices of Game Design & Indie Game Marketing, includes chapters from The Art of Game Design: A Book of Lenses, A Practical Guide to Indie Game Marketing, and An Architectural Approach to Level Design. The GameDev.net FreeBook is relevant to game designers, developers, and those interested in learning more about the challenges in game development. We know game development can be a tough discipline and business, so we picked several chapters from CRC Press titles that we thought would be of interest to you, the GameDev.net audience, in your journey to design, develop, and market your next game. The free ebook is available through CRC Press by clicking here. The Curated Books The Art of Game Design: A Book of Lenses, Second Edition, by Jesse Schell Presents 100+ sets of questions, or different lenses, for viewing a game’s design, encompassing diverse fields such as psychology, architecture, music, film, software engineering, theme park design, mathematics, anthropology, and more. Written by one of the world's top game designers, this book describes the deepest and most fundamental principles of game design, demonstrating how tactics used in board, card, and athletic games also work in video games. It provides practical instruction on creating world-class games that will be played again and again. View it here. A Practical Guide to Indie Game Marketing, by Joel Dreskin Marketing is an essential but too frequently overlooked or minimized component of the release plan for indie games. A Practical Guide to Indie Game Marketing provides you with the tools needed to build visibility and sell your indie games. With special focus on those developers with small budgets and limited staff and resources, this book is packed with tangible recommendations and techniques that you can put to use immediately. As a seasoned professional of the indie game arena, author Joel Dreskin gives you insight into practical, real-world experiences of marketing numerous successful games and also provides stories of the failures. View it here. An Architectural Approach to Level Design This is one of the first books to integrate architectural and spatial design theory with the field of level design. The book presents architectural techniques and theories for level designers to use in their own work. It connects architecture and level design in different ways that address the practical elements of how designers construct space and the experiential elements of how and why humans interact with this space. Throughout the text, readers learn skills for spatial layout, evoking emotion through gamespaces, and creating better levels through architectural theory. View it here. Learn more and download the ebook by clicking here. Did you know? GameDev.net and CRC Press also recently teamed up to bring GDNet+ Members up to a 20% discount on all CRC Press books. Learn more about this and other benefits here.
Sign in to follow this  
Followers 0
mr5

Separate matrices for every glDrawCalls

3 posts in this topic

Hello and Good day!

I would like to ask if it is efficient that each glDrawCalls has its own matrix?

e.g:

class Object
{
public:

    void draw();

    int x;
    int y;
    int z;
 protected:

    Object* child;
};

//Implementation # 1
void Object::draw()
{
    glPushMatrix();
    glTranslatef(x, y, z);
    ...
    glPopMatrix();
    //Use separate matrix for every this->child
    for (auto &i : child)
    {
        i->draw();
    }
}
//Implementation # 2
void Object::draw()
{
    glPushMatrix();
    glTranslatef(x, y, z);
    ...
    //Used single matrix on each this->child
    for (auto &i : child)
    {
        i->draw();
    }
    glPopMatrix();
}

The child I am referring to is/are the object(s) the will be drawn on top of the parent.

The child's coordinate(x, y) will almost always lie on the parent's body.

This implementation is easy to write and easy to comprehend but,

I'm not satisfied because I could have just use  glPushMatrix  and glPopMatrix once for every parent I will render  then glTranslatex a little bit the child object but,

if I do it this way, it'll be hard for me to find the child's coordinate.

For example in a hover effect this would become:

if (obj->contains(parent.x + mouse.x, parent.y + moue.y))
{
    //do hover effect!
}

instead of just

if (obj->contains(mouse.x, mouse.y)
{
    //do hover effect!
}

I will need an extra calculation for this to achieve and my code will become more messy. What could be the alternative way to figure out the location of each object drawn by the parent?

 

Thanks and regards biggrin.png

Edited by mr5
0

Share this post


Link to post
Share on other sites

I can't really see your problem. You can create a function that returns the world client position, and use it when you want.
Also, i would have made a struct/class for points/vectors, so that you could easily handle coordinates. 

// Example of how a Vector3 struct may look like
struct Vector3
{
    int x, y, z;
    Vector3(int x, int y, int z) : x(x), y(y), z(z) {}

    void set(int x, int y, int z)
    {
        x = x;
        y = y;
        z = z;
    }

    Vector3 operator+(const Vector3 &a) const
    {
        return Vector3(x + a.x, y + a.y, z + a.z);
    }

    /* ... add some other neat functions ... */
};

// Example #1
Vector3 Object::getWorldCoord()
{
    Vector3 result;
    if(parent)
    {
        result = parent->getWorldCoord() + m_position; // position is a Vector3, and is a member of the Object class.
    }
    else
    {
        result = m_position;
    }
    return result;
}

// Example #2 that works out of the box for you
void Object::getWorldCoord(int &outX, int &outY, int &outZ) 
{
    if(parent)
    {
        int parentX, parentY, parentZ;
        parent->getWorldCoord(parentX, parentY, parentZ);
        outX = parentX + x; 
        outY = parentY + y; 
        outZ = parentZ + z;
    }
    else
    {
        outX = x;
        outY = y;
        outZ = z;
    } 
}

Edited by Tapped
0

Share this post


Link to post
Share on other sites

@Tapped:

For your getWorldCoord() functions, I think the case where parent is true should be different, if you want to support nested parenting.

m_position is basically the offset from either origin or parent (whichever is applicable), but your code won't work correctly if the parent also has a parent.

"Box on top of table" would work, but "Book on top of box on top of table" wouldn't.

 

I think [i]parent->m_position[/i] should instead be [i]parent->getWorldCoord()[/i].

A similar fix would be needed for your second example.

1

Share this post


Link to post
Share on other sites

@Tapped:

For your getWorldCoord() functions, I think the case where parent is true should be different, if you want to support nested parenting.

m_position is basically the offset from either origin or parent (whichever is applicable), but your code won't work correctly if the parent also has a parent.

"Box on top of table" would work, but "Book on top of box on top of table" wouldn't.

 

I think parent->m_position should instead be parent->getWorldCoord().

A similar fix would be needed for your second example.

 

Thanks for pointing that out, i have edited the post.

0

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0