float back_dist;
// all movement is based on t_frame.
-float t_frame; // length of this frame (in ticks = 1/20th second)
+float t_frame; // length of this frame (in ticks = 1/20th second) adjusted for gamespeed
int ms_frame; // length of this frame (milliseconds)
int ms_end; // end of this frame (milliseconds)
void
new_bang_dots(int xbang, int ybang, int dx, int dy, SDL_Surface *s)
{
- int i, x, y;
+ int i, n, x, y;
uint16_t *pixel, c;
uint32_t colorkey;
int row_inc;
double theta, r;
+ n = 24.0 * t_frame;
pixel = s->pixels;
row_inc = s->pitch/sizeof(uint16_t) - s->w;
colorkey = s->format->colorkey;
SDL_LockSurface(s);
- for(i=0; i<10; i++) {
+ for(i=0; i<n; i++) {
pixel = s->pixels;
for(y=0; y<s->h; y++) {
for(x = 0; x<s->w; x++) {
bdot[bd2].dy = 45*r*sin(theta) + dy;
bdot[bd2].x = x + xbang;
bdot[bd2].y = y + ybang;
- bdot[bd2].c = 0;
+ bdot[bd2].c = (i < n-3) ? 0 : c;
bdot[bd2].life = 100;
bdot[bd2].decay = frnd()*3 + 1;
bdot[bd2].active = 1;
- // Replace the last few bang dots with the pixels from the exploding object
- if(i>6) bdot[bd2].c = c;
-
bd2 = (bd2+1) % MAXBANGDOTS;
}
pixel += row_inc;
}
void
-draw_bang_dots(SDL_Surface *s)
+move_bang_dots(float ticks)
{
int i;
- int first_i, last_i;
- uint16_t *pixels, *pixel, c;
- int row_inc = s->pitch/sizeof(uint16_t);
Sprite *hit;
- pixels = (uint16_t *) s->pixels;
- first_i = -1;
- last_i = 0;
-
for(i=0; i<MAXBANGDOTS; i++) {
if(!bdot[i].active) continue;
// decrement life and maybe kill
bdot[i].life -= bdot[i].decay;
- if(bdot[i].life<0) { bdot[i].active = 0; continue; }
-
+ if(bdot[i].life < 0) { bdot[i].active = 0; continue; }
+
// move and clip
- bdot[i].x += (bdot[i].dx - screendx)*t_frame;
- bdot[i].y += (bdot[i].dy - screendy)*t_frame;
+ bdot[i].x += (bdot[i].dx - screendx)*ticks;
+ bdot[i].y += (bdot[i].dy - screendy)*ticks;
if(bdot[i].x < 0 || bdot[i].x >= XSIZE || bdot[i].y < 0 || bdot[i].y >= YSIZE) {
bdot[i].active = 0;
continue;
continue;
}
}
+ }
+}
+
+
+void
+draw_bang_dots(SDL_Surface *s)
+{
+ int i;
+ uint16_t *pixels, *pixel, c;
+ int row_inc = s->pitch/sizeof(uint16_t);
+
+ pixels = (uint16_t *) s->pixels;
+
+ for(i=0; i<MAXBANGDOTS; i++) {
+ if(!bdot[i].active) continue;
pixel = pixels + row_inc*(int)(bdot[i].y) + (int)(bdot[i].x);
if(bdot[i].c) c = bdot[i].c; else c = heatcolor[(int)(bdot[i].life)*3];
void
-new_engine_dots(int n, int dir) {
+new_engine_dots(float time_span, int dir) {
int i;
+ int n = time_span * ENGINE_DOTS_PER_TIC;
float a, r; // angle, random length
float dx, dy;
float hx, hy; // half ship width/height.
static const int s[4] = { 2, 1, 0, 1 };
+ float time;
+ float accelh, accelv, past_ship_dx, past_ship_dy;
hx = ship.image->w / 2;
hy = ship.image->h / 2;
dy = r * -sin(a); // screen y is "backwards".
dotptr->active = 1;
- dotptr->x = ship.x + s[dir]*hx + (frnd()-0.5)*3;
- dotptr->y = ship.y + s[(dir+1)&3]*hy + (frnd()-0.5)*3;
+
+ // dot was created at a random time during the time span
+ time = frnd() * time_span; // this is how long ago
+
+ // calculate how fast the ship was going when this engine dot was
+ // created (as if it had a smooth acceleration). This is used in
+ // determining the velocity of the dots, but not their starting
+ // location.
+ accelh = ((ship.jets >> 2) & 1) - (ship.jets & 1);
+ accelh *= THRUSTER_STRENGTH * time;
+ past_ship_dx = ship.dx - accelh;
+ accelv = ((ship.jets >> 1) & 1) - ((ship.jets >> 3) & 1);
+ accelv *= THRUSTER_STRENGTH * time;
+ past_ship_dy = ship.dy - accelv;
+
+ // the starting position (not speed) of the dot is calculated as
+ // though the ship were traveling at a constant speed for this
+ // time_span.
+ dotptr->x = (ship.x - (ship.dx - screendx) * time) + s[dir]*hx;
+ dotptr->y = (ship.y - (ship.dy - screendy) * time) + s[(dir+1)&3]*hy;
if(dir&1) {
- dotptr->dx = ship.dx + 2*dx;
- dotptr->dy = ship.dy + 20*dy;
+ dotptr->dx = past_ship_dx + 2*dx;
+ dotptr->dy = past_ship_dy + 20*dy;
dotptr->life = 60 * fabs(dy);
} else {
- dotptr->dx = ship.dx + 20*dx;
- dotptr->dy = ship.dy + 2*dy;
+ dotptr->dx = past_ship_dx + 20*dx;
+ dotptr->dy = past_ship_dy + 2*dy;
dotptr->life = 60 * fabs(dx);
}
+ // move the dot as though it were created in the past
+ dotptr->x += (dotptr->dx - screendx) * time;
+ dotptr->y += (dotptr->dy - screendy) * time;
+
if(dotptr - edot < MAXENGINEDOTS-1) dotptr++;
else dotptr = edot;
}
}
void
-draw_engine_dots(SDL_Surface *s) {
+move_engine_dots(float ticks) {
int i;
- uint16_t c;
- uint16_t *pixels = (uint16_t *) s->pixels;
- int row_inc = s->pitch/sizeof(uint16_t);
- int heatindex;
Sprite *hit;
for(i = 0; i<MAXENGINEDOTS; i++) {
if(!edot[i].active) continue;
- edot[i].x += (edot[i].dx - screendx)*t_frame;
- edot[i].y += (edot[i].dy - screendy)*t_frame;
+
+ edot[i].x += (edot[i].dx - screendx)*ticks;
+ edot[i].y += (edot[i].dy - screendy)*ticks;
edot[i].life -= t_frame*3;
- if(edot[i].life < 0
- || edot[i].x<0 || edot[i].x >= XSIZE
- || edot[i].y<0 || edot[i].y >= YSIZE) {
+ if(edot[i].life < 0 || edot[i].x<0 || edot[i].x >= XSIZE || edot[i].y < 0 || edot[i].y >= YSIZE) {
edot[i].active = 0;
- continue;
}
+
// check collisions
if((hit = pixel_collides(edot[i].x, edot[i].y))) {
if(hit->type != SHIP) { // they shouldn't hit the ship, but they do
continue;
}
}
+ }
+}
+
+void
+draw_engine_dots(SDL_Surface *s) {
+ int i;
+ uint16_t c;
+ uint16_t *pixels = (uint16_t *) s->pixels;
+ int row_inc = s->pitch/sizeof(uint16_t);
+ int heatindex;
+
+ for(i = 0; i<MAXENGINEDOTS; i++) {
+ if(!edot[i].active) continue;
+
heatindex = edot[i].life * 6;
c = heatindex>3*W ? heatcolor[3*W-1] : heatcolor[heatindex];
pixels[row_inc*(int)(edot[i].y) + (int)(edot[i].x)] = c;
}
void
-drawdots(SDL_Surface *s) {
+draw_dots(SDL_Surface *s) {
int m;
- // Create engine dots out the side we're moving from
+ // Create engine dots
for(m = 0; m<4; m++) {
if(ship.jets & 1<<m) { // 'jets' is a bit field
- new_engine_dots(200.0*t_frame,m);
+ new_engine_dots(t_frame,m);
}
}
- move_dust();
-
SDL_LockSurface(s);
draw_dust(s);
draw_engine_dots(s);
draw(void) {
SDL_FillRect(surf_screen,NULL,0); // black background
- drawdots(surf_screen); // background dots
+ draw_dots(surf_screen); // background dots
draw_sprite(SPRITE(&ship));
draw_rocks();
}
}
- new_rocks();
-
// SCROLLING
tmp = (ship.y+ship.dy*t_frame-YSCROLLTO)/25 + (ship.dy-screendy);
screendy += tmp * t_frame/12;
bangx += (bangdx - screendx)*t_frame;
bangy += (bangdy - screendy)*t_frame;
- move_sprites();
-
+ move_sprites(t_frame);
+ move_engine_dots(t_frame);
+ move_bang_dots(t_frame);
+ move_dust(t_frame);
// BOUNCE off left or right edge of screen
if(ship.x < 0 || ship.x+ship.w > XSIZE) {
ship.dy = screendy - (ship.dy-screendy)*opt_bounciness;
}
+ new_rocks(t_frame);
+
draw();
if(state == GAMEPLAY && bang) {
if(state == GAMEPLAY) {
if(!paused) {
- if(keystate[SDLK_LEFT] | keystate[SDLK_h]) { ship.dx -= 1.5*t_frame; ship.jets |= 1<<0;}
- if(keystate[SDLK_DOWN] | keystate[SDLK_t]) { ship.dy += 1.5*t_frame; ship.jets |= 1<<1;}
- if(keystate[SDLK_RIGHT] | keystate[SDLK_n]) { ship.dx += 1.5*t_frame; ship.jets |= 1<<2;}
- if(keystate[SDLK_UP] | keystate[SDLK_c]) { ship.dy -= 1.5*t_frame; ship.jets |= 1<<3;}
+ // FIXME why is this at the bottom? Shouldn't it be up before the ship movement?
+ if(keystate[SDLK_LEFT] || keystate[SDLK_h]) { ship.dx -= THRUSTER_STRENGTH*t_frame; ship.jets |= 1<<0;}
+ if(keystate[SDLK_DOWN] || keystate[SDLK_t]) { ship.dy += THRUSTER_STRENGTH*t_frame; ship.jets |= 1<<1;}
+ if(keystate[SDLK_RIGHT] || keystate[SDLK_n]) { ship.dx += THRUSTER_STRENGTH*t_frame; ship.jets |= 1<<2;}
+ if(keystate[SDLK_UP] || keystate[SDLK_c]) { ship.dy -= THRUSTER_STRENGTH*t_frame; ship.jets |= 1<<3;}
if(keystate[SDLK_3]) { SDL_SaveBMP(surf_screen, "snapshot.bmp"); }
}