LinuxQuestions.org - C++/SDL: Images moving too slowly. Images loaded once, etc. Why?

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C++/SDL: Images moving too slowly. Images loaded once, etc. Why?

I am looking at games on the Super Nintendo, NES and etc., and I noticed how smooth their backgrounds and other objects move across the screen. I'm trying to recreate that after a couple unsuccessful attempts. I have made a small program that just moves a stick man across the screen everywhere, except where some blocks are at.

http://www.yousendit.com/transfer.ph...E52A1E3A0EF883

Just execute sc_game and you can see what I mean.

I am trying to get speed variation in my objects. So far, to get that smoothness I see in 2D games, moving images one pixel at a time across the screen using a specific time frame for each image sounds like the best way to achieve this.

The problem with the above application is that it does not use a time frame. And strangely, it is running strangely slow. Why?

Am I supposed to move images across the screen by the pixels (instead of one) along with a time frame?

Thanks in advance.

Currently your object "blob" just updates positions using a defined offset

Code:

void scobject::move ()

{

        switch ( move_x )

        {

                case LEFT : xywh.x -= offsetX; break;

                case RIGHT: xywh.x += offsetY; break;

                case STOP :                    break;

...

The simplest method to use is linear interpolation with each frame having a time step.
Using a fixed time step can help in making a game run the same no matter what the machine specs are, where as a variable time step gives differing results.

Code:

struct Object

{

        float x,y;//position

        float vx,vy;//velocity



        update(float time_step)

        {

                //v = u + at

                //position = initial + velocity * time

                x += vx * time_step;

                y += vy * time_step;



        }

};

Here is two links from Glenn Fiedler that you should read:
http://www.gaffer.org/game-physics/fix-your-timestep/
http://www.gaffer.org/game-physics/integration-basics/

Thank you, I am implemented time based movement into my game.