shot and diagonal movents

shot and diagonal movents

dengue

Member #12,790

April 2011

hi ,i dont speak very well english(i speak spanish) so i will try be very puntual in the things that i need help.
I need to do sometime like the game geometry wars.
The first problem is that i have adaptet de diagonal movent but i can't adapt the movent to diagonal imagenes, i dont know how do it, the second problem is that i need that when the users press the arrow keys, a shot go in the direction of the arrow key, the problem is that i dont know how make that the shot continue in the direction that the arrow key indicates, i think that i need like use the timer but i haven´t seen a example for that, please help, and sorry for my english;D

Edgar Reynaldo

Major Reynaldo

May 2007

Dengue said:

The first problem is that i have adaptet de diagonal movent but i can't adapt the movent to diagonal imagenes, i dont know how do it,

You need to keep track of position, speed, and the angle of your object :

#SelectExpand
  1#include <math.h>
  2
  3typedef struct Moveable {
  4   float x;     // x position
  5   float y;     // y position
  6   float xvel;  // x velocity
  7   float yvel;  // y velocity
  8   float speed; // total speed
  9   float angle; // angle in degrees
 10};
 11
 12Moveable NewMoveable(int x , int y , float speed , float angle) {
 13   Moveable m;
 14   m.x = x;
 15   m.y = y;
 16   SetSpeedAndAngle(&m , speed , angle);
 17   return m;
 18}
 19
 20void SetSpeedAndAngle(Moveable* m , float speed , float angle) {
 21   m->speed = speed;
 22   m->angle = angle;
 23   m->xvel = speed*cos(angle*((2.0f*M_PI)/360.0f));
 24   m->yvel = speed*sin(angle*((2.0f*M_PI)/360.0f));
 25}
 26
 27void Move(Moveable* m) {
 28   m->x += m->xvel;
 29   m->y += m->yvel;
 30}

Example usage :

Moveable m = NewMoveable(x , y , 25.0f/60.0f , 45.0);// Moves 25 pixels per second down and right

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weapon_S

Member #7,859

October 2006

I can't really figure out what you are doing at the moment, but it seems you use a fixed set of bitmaps. And you seem to have player input combined with updating the ship.
What you'll want to do is something like:
detect input;
update world (use input; move according to time passed; handle collisions/other game events);
blit to screen;
repeat;

You might want to look into storing the player's (and bullet's) directions as an angle and using rotate_sprite. Then it will also get a speed. (And only in the 'update' part of the program, the speed will have effect.)

Some other remarks.
if(x==0){rest(50);}
Very bad way to handle boundaries, at a very bad place in your code (player input != collision detection). Also don't use rest...
[edit]Beaten by 20 minutes WTF I didn't use so much time writing this.
There are enough examples of timers. Search for 'timer' & 'speed', or 'game loop'.

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Edgar Reynaldo

Major Reynaldo

May 2007

I didn't see the attached file before, but after looking at it I have a few comments :

main.cpp said:

class Nave {
//...
        BITMAP *imagenes[9];
};
//...
Nave::~Nave(){
    delete [] imagenes;
};

Don't use delete on a pointer that you didn't use new to create. Use destroy_bitmap on imagenes[0] thru imagenes[8] instead.

Your MoverX and MoverY functions should not draw anything to the screen, they should only change the position of your objects.

Separate logic and drawing.

You don't clear_to_color on your buffer, so your program must look pretty messy right now.

You use draw_sprite to draw the buffer, but you should use blit instead.

Desmond Taylor

Member #11,943

May 2010

Thanks Edgar Reynaldo, That code that you posted helped me I was trying to do this too but as normal I use Search and Recent on these boards to see if it's been covered else I was just about to post

Thanks again

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dengue

Member #12,790

April 2011

thanks Edgar Reynaldo and weapon_S, i am reading the articles of the angles and i am editing my code, thanks a lot