parable C

#include <oslib/oslib.h>
#include "methods.h"

PSP_MODULE_INFO("Test", 0, 1, 1);
PSP_MAIN_THREAD_ATTR(THREAD_ATTR_USER | THREAD_ATTR_VFPU);


float gravity, angle, speed;
float x, y;
void oslDrawParable(float x0, float y0, float speed, float angle, float gravity, int length, OSL_COLOR color);

int main(void) {
    oslInit(0);
    oslInitGfx(OSL_PF_8888, 1);
    oslIntraFontInit(INTRAFONT_CACHE_MED);

    x = 20;
    y = 262;

    gravity = 9.8;
    speed = 45;
    angle = 340;

    while(!osl_quit){
        CleanRead();
        oslDrawLine(0, 262, 480, 262, RGB(255, 0, 0));

        //if(osl_keys->pressed.cross)
            //drawParable(x, y, speed, angle, gravity);
            oslDrawParable(x, y, speed, angle, gravity, 50, RGB(0, 0, 255));
        //Angle
            if(osl_keys->held.L)   angle -= 1;
            if(osl_keys->held.R)   angle += 1;
        //X,Y
            if(abs(osl_keys->analogY) > 50){
                y = y +osl_keys->analogY/50 ;
            }
            if(abs(osl_keys->analogX) > 50){
                x = x + osl_keys->analogX/50 ;
            }
        //Speed
            if(osl_keys->held.right)    speed += 0.1;
            if(osl_keys->held.left)     speed -= 0.1;
        //Gravity
            if(osl_keys->held.up)    gravity += 0.05;
            if(osl_keys->held.down)  gravity -= 0.05;

        oslDrawLine(x, y-10, x, y+10, RGB(0, 0, 0));
        oslDrawLine(x-10, y, x+10, y, RGB(0, 0, 0));
        oslDrawLine(x , y, x + cos( toRad(angle) )* 40, y + sin( toRad(angle) )* 40, RGB(255, 0, 255));

        oslDrawStringf(5, 5, "angle: %i", (int)angle);
        oslDrawStringf(5, 15, "x: %i  y: %i ", (int)x, (int)y);
        oslDrawStringf(5, 25, "speed: %f   gravity: %f", speed, gravity);
        Render();
    }

    oslEndGfx();
    oslQuit();
    return 0;
}

void oslDrawParable(float x0, float y0, float speed, float angle, float gravity, int length, OSL_COLOR color){
    if(speed == 0.0f) return;
    int i;
    float x, y, oldx, oldy, speed_x, speed_y;
    speed_x = oslCosf( toRad(angle) ) * speed;
    speed_y = oslSinf( toRad(angle) ) * speed;
    oldx = x0;
    oldy = y0;
    for(i = 0; i < length; i++){
        x = x0 + speed_x*i;
        y = y0 + speed_y*i + (gravity/2) * (i*i);
        oslDrawLine(oldx, oldy, x, y, color);
        oldx = x;
        oldy = y;

    }
}