X-Git-Url: https://jasonwoof.com/gitweb/?p=vor.git;a=blobdiff_plain;f=sprite.c;h=447e4827525329005a673f07b098d5115227d902;hp=ca3e937ab21cfc0e940572c5ed43dafe351ce06e;hb=148882a3cc520f34616a1175ed157fe258d68dcc;hpb=f33f1a05297ce0156030f0f78ecf5b84e00d424c

diff --git a/sprite.c b/sprite.c
index ca3e937..447e482 100644
--- a/sprite.c
+++ b/sprite.c
@@ -1,121 +1,448 @@
+#include <math.h>
 #include <stdlib.h>
+#include <string.h>
+#include "config.h"
 #include "common.h"
+#include "globals.h"
 #include "sprite.h"
+#include "rocks.h"
 
-void
-get_shape(SDL_Surface *img, struct shape *s)
+SDL_Surface *load_image(char *filename);
+void load_ship(void);
+
+// 2 sets of sprites, sorted by position
+static Sprite **sprites[2] = { NULL, NULL };
+
+// which set are we using?
+static int set = 0;
+
+// size of squares into which sprites are sorted.
+static int grid_size = 0;
+
+// screen size in grid squares.
+static int gw = 0, gh = 0;
+
+// lists of free sprites, by type.
+Sprite *free_sprites[N_TYPES];
+
+
+static void
+get_shape(Sprite *s)
 {
 	int x, y;
 	uint16_t *px, transp;
 	uint32_t bits = 0, bit, *p;
 
-	if(img->format->BytesPerPixel != 2) {
+	s->area = 0;
+	if(s->image->format->BytesPerPixel != 2) {
 		fprintf(stderr, "get_shape(): not a 16-bit image!\n");
 		exit(1);
 	}
 
-	s->area = 0;
-	s->w = img->w; s->h = img->h;
-	s->mw = ((img->w+31)>>5);
-	s->mask = malloc(4*s->mw*s->h);
+	s->w = s->image->w; s->h = s->image->h;
+	grid_size = max(grid_size, max(s->w, s->h));
+	s->mask_w = ((s->w+31)>>5);
+	s->mask = malloc(s->mask_w*s->h*sizeof(uint32_t));
 	if(!s->mask) {
-		fprintf(stderr, "can't malloc bitmask");
+		fprintf(stderr, "get_shape(): can't allocate bitmask.\n");
 		exit(1);
 	}
 
-	SDL_LockSurface(img);
-	px = img->pixels;
-	transp = img->format->colorkey;
+	SDL_LockSurface(s->image);
+	px = s->image->pixels;
+	transp = s->image->format->colorkey;
 	p = s->mask;
-	for(y=0; y<img->h; y++) {
+	for(y=0; y<s->image->h; y++) {
 		bit = 0;
-		for(x=0; x<img->w; x++) {
+		for(x=0; x<s->image->w; x++) {
 			if(!bit) { bits = 0; bit = 0x80000000; }
 			if(*px++ != transp) { bits |= bit; s->area++; }
 			bit >>= 1;
-			if(!bit || x == img->w - 1) { *(p++) = bits; }
+			if(!bit || x == s->image->w - 1) { *(p++) = bits; }
 		}
-		px = (uint16_t *) ((uint8_t *) px + img->pitch - 2*img->w);
+		px = (uint16_t *) ((uint8_t *) px + s->image->pitch - 2*s->image->w);
 	}
-	SDL_UnlockSurface(img);
+	SDL_UnlockSurface(s->image);
 }
 
-int
-line_collide(int xov, struct shape *r, uint32_t *rbits, struct shape *s, uint32_t *sbits)
+
+void
+load_sprite(Sprite *s, char *filename)
 {
-	int lshift, n, i, ret = 0;
-	uint32_t lbits;
-	struct shape *st;
-	uint32_t *bt;
+	s->image = load_image(filename);
+	if(s->image) get_shape(s);
+}
+
 
+static void
+load_sprites(void)
+{
+	load_ship();
+	load_rocks();
+}
 
-	if(xov < 0) {
-		st = r; r = s; s = st;
-		bt = rbits; rbits = sbits; sbits = bt;
-		xov = -xov;
+
+void
+init_sprites(void)
+{
+	load_sprites();
+
+	grid_size = grid_size * 3 / 2;
+	gw = (XSIZE-1 + 2*grid_size) / grid_size;
+	gh = (YSIZE-1 + 2*grid_size) / grid_size;
+
+	sprites[0] = malloc(2 * gw * gh * sizeof(Sprite *));
+	sprites[1] = (void *)sprites[0] + gw * gh * sizeof(Sprite *);
+	if(!sprites[0]) {
+		fprintf(stderr, "init_sprites(): can't allocate grid squares.\n");
+		exit(1);
 	}
+	memset(sprites[0], 0, 2 * gw * gh * sizeof(Sprite *));
+	set = 0;
+}
+
+static inline Sprite **
+square(int x, int y, int set)
+{
+	int b = (x+grid_size)/grid_size + gw*((y+grid_size)/grid_size);
+	return &sprites[set][b];
+}
 
+void
+add_sprite(Sprite *s)
+{
+	insert_sprite(square(s->x, s->y, set), s);
+}
+
+void
+reset_sprites(void)
+{
+	int i;
 
-	lshift = (r->w - xov) & 31; 
-	rbits += (r->w - xov) >> 5;
-	n = (xov + 31) >> 5;
-	for(i=0; i<n-1; i++) {
-		lbits = *rbits++ << lshift;
-		lbits |= *rbits >> (32 - lshift);
-		if(lbits & *sbits++) ret = 1;
+	for(i=0; i<gw*gh; i++)
+		while(sprites[set][i]) {
+			Sprite *s = remove_sprite(&sprites[set][i]);
+			insert_sprite(&free_sprites[s->type], s);
+			s->flags = 0;
+		}
+}
+
+void
+move_sprite(Sprite *s)
+{
+	if(s->flags & MOVE) {
+		s->x += (s->dx - screendx)*t_frame;
+		s->y += (s->dy - screendy)*t_frame;
 	}
-	lbits = *rbits << lshift;
-	if(lbits & *sbits) ret = 1;
+}
 
-	return ret;
+void
+sort_sprite(Sprite *s)
+{
+	// clip it, or sort it into the other set of sprites.
+	if(s->x + s->w < 0 || s->x >= XSIZE
+	   || s->y + s->h < 0 || s->y >= YSIZE) {
+		insert_sprite(&free_sprites[s->type], s);
+		s->flags = 0;
+	} else insert_sprite(square(s->x, s->y, 1-set), s);
 }
 
-int
-mask_collide(int xov, int yov, struct shape *r, struct shape *s)
+void
+move_sprites(void)
+{
+	int sq;
+	Sprite **head;
+
+	// Move all the sprites
+	for(sq=0; sq<gw*gh; sq++) {
+		head=&sprites[set][sq];
+		while(*head) {
+			Sprite *s = remove_sprite(head);
+			move_sprite(s); sort_sprite(s);
+		}
+	}
+	set = 1-set;  // switch to other set of sprites.
+}
+
+
+static int
+line_collide(int xov, unsigned bit, uint32_t *amask, uint32_t *bmask)
+{
+	int i, words = (xov-1) >> 5;
+	uint32_t abits;
+
+	for(i=0; i<words; i++) {
+		abits = *amask++ << bit;
+		abits |= *amask >> (32-bit);
+		if(abits & *bmask++) return true;
+	}
+	abits = *amask << bit;
+	if(abits & *bmask) return true;
+
+	return false;
+}
+
+static int
+mask_collide(int xov, int yov, Sprite *a, Sprite *b)
 {
-	int y, ry, sy;
-	uint32_t *rbits, *sbits;
+	int y;
+	int xoffset = a->w - xov;
+	int word = xoffset >> 5, bit = xoffset & 31;
+	uint32_t *amask = a->mask, *bmask = b->mask;
 
 	if(yov > 0) {
-		ry = r->h - yov; sy = 0;
-		rbits = r->mask + (r->h - yov) * r->mw;
-		sbits = s->mask;
+		amask = a->mask + ((a->h - yov) * a->mask_w) + word;
+		bmask = b->mask;
 	} else {
-		ry = 0; sy = s->h + yov;
-		rbits = r->mask;
-		sbits = s->mask + (s->h + yov) * s->mw;
+		yov = -yov;
+		amask = a->mask;
+		bmask = b->mask + ((b->h - yov) * b->mask_w) + word;
 	}
 
-	for(y=0; y<abs(yov); y++) {
-		if(line_collide(xov, r, rbits, s, sbits)) return 1;
-		rbits += r->mw; sbits += s->mw;
+	for(y=0; y<yov; y++) {
+		if(line_collide(xov, bit, amask, bmask)) return 1;
+		amask += a->mask_w; bmask += b->mask_w;
 	}
 
 	return 0;
 }
 
 int
-collide(int xdiff, int ydiff, struct shape *r, struct shape *s)
+collide(Sprite *a, Sprite *b)
+{
+	int dx, dy, xov, yov;
+
+	if(!COLLIDES(a) || !COLLIDES(b)) return false;
+
+	if(b->x < a->x) { Sprite *tmp = a; a = b; b = tmp; }
+
+	dx = b->x - a->x;
+	dy = b->y - a->y;
+
+	xov = max(min(a->w - dx, b->w), 0);
+
+	if(dy >= 0) yov = max(min(a->h - dy, b->h), 0);
+	else yov = -max(min(b->h - -dy, a->h), 0);
+
+	if(xov == 0 || yov == 0) return false;
+	else return mask_collide(xov, yov, a, b);
+}
+
+void
+collide_with_list(Sprite *s, Sprite *list)
+{
+	for(; list; list=list->next)
+		if(collide(s, list)) do_collision(s, list);
+}
+
+void
+collisions(void)
+{
+	int i, end = gw*gh;
+	Sprite *s;
+	for(i=0; i<end; i++) {
+		for(s=sprites[set][i]; s; s=s->next) {
+			collide_with_list(s, s->next);
+			if(i+1 < end) collide_with_list(s, sprites[set][i+1]);
+			if(i+gw < end) collide_with_list(s, sprites[set][i+gw]);
+			if(i+gw+1 < end) collide_with_list(s, sprites[set][i+gw+1]);
+		}
+	}
+}
+
+Sprite *
+hit_in_square(Sprite *r, Sprite *s)
+{
+	for(; r; r=r->next)
+		if(collide(r, s)) break;
+	return r;
+}
+
+Sprite *
+collides(Sprite *s)
 {
-	int xov, yov;
+	int l, r, t, b;
+	Sprite **sq;
+	Sprite *c;
 
-	if(xdiff >= 0) xov = max(min(r->w-xdiff, s->w), 0);
-	else xov = min(-min(s->w+xdiff, r->w), 0);
+	l = (s->x + grid_size) / grid_size;
+	r = (s->x + s->w + grid_size) / grid_size;
+	t = (s->y + grid_size) / grid_size;
+	b = (s->y + s->h + grid_size) / grid_size;
+	sq = &sprites[set][l + t*gw];
 
-	if(ydiff >= 0) yov = max(min(r->h-ydiff, s->h), 0);
-	else yov = min(-min(s->h+ydiff, r->h), 0);
+	if((c = hit_in_square(*sq, s))) return c;
+	if(l > 0 && (c = hit_in_square(*(sq-1), s))) return c;
+	if(t > 0 && (c = hit_in_square(*(sq-gw), s))) return c;
+	if(l > 0 && t > 0 && (c = hit_in_square(*(sq-1-gw), s))) return c;
 
-	if(xov == 0 || yov == 0) return 0;  // bboxes hit?
-	else return mask_collide(xov, yov, r, s);
+	if(r > l) {
+		if((c = hit_in_square(*(sq+1), s))) return c;
+		if(t > 0 && hit_in_square(*(sq+1-gw), s)) return c;
+	}
+	if(b > t) {
+		if((c = hit_in_square(*(sq+gw), s))) return c;
+		if(l > 0 && (c = hit_in_square(*(sq-1+gw), s))) return c;
+	}
+	if(r > l && b > t && (c = hit_in_square(*(sq+1+gw), s))) return c;
+	return NULL;
 }
 
 int
-pixel_collide(unsigned int xoff, unsigned int yoff, struct shape *r)
+pixel_collide(Sprite *s, int x, int y)
 {
 	uint32_t pmask;
+
+	if(!COLLIDES(s)) return false;
 	
-	if(xoff >= r->w || yoff >= r->h) return 0;
+	if(x < s->x || y < s->y || x >= s->x + s->w || y >= s->y + s->h) return 0;
+
+	x -= s->x; y -= s->y;
+	pmask = 0x80000000 >> (x&0x1f);
+	return s->mask[(y*s->mask_w) + (x>>5)] & pmask;
+}
+
+Sprite *
+pixel_hit_in_square(Sprite *r, float x, float y)
+{
+	for(; r; r=r->next) {
+		if(COLLIDES(r) && pixel_collide(r, x, y)) return r;
+	}
+	return 0;
+}
+
+Sprite *
+pixel_collides(float x, float y)
+{
+	int l, t;
+	Sprite **sq;
+	Sprite *ret;
+
+	l = (x + grid_size) / grid_size; t = (y + grid_size) / grid_size;
+	sq = &sprites[set][l + t*gw];
+	if((ret = pixel_hit_in_square(*sq, x, y))) return ret;
+	if(l > 0 && (ret = pixel_hit_in_square(*(sq-1), x, y))) return ret;
+	if(t > 0 && (ret = pixel_hit_in_square(*(sq-gw), x, y))) return ret;
+	if(l > 0 && t > 0 && (ret = pixel_hit_in_square(*(sq-1-gw), x, y))) return ret;
+	return 0;
+}
+
+
+float
+sprite_mass(Sprite *s)
+{
+	if(s->type == SHIP) return s->area;
+	else if(s->type == ROCK) return 3 * s->area;
+	else return 0;
+}
+
+/*
+ * BOUNCE THEORY
+ *
+ * ******************  In 1 Dimension  *****************
+ *
+ * For now we will imagine bouncing A and B off each other in 1 dimension (along
+ * a line). We can safely save the other dimension for later.
+ *
+ * A and B are the same weight, and are both traveling 1m/sec, to collide right
+ * at the origin. With perfect bounciness, their full momentum is reversed.
+ *
+ * If we cut the weight of A down by half, then the center of our colision will
+ * drift towards A (the speeds of A and B are not simply reversed as in our last
+ * example.) However, there is always a place between A and B on the line (I'll
+ * call it x) such that the speeds of A and B relative to x, are simply
+ * reversed. Thus we can find the new speed for A like so:
+ *
+ *     new A = x -(A - x)
+ *
+ *     new B = x -(B - x)
+ * 
+ * or, simply:
+ *
+ *     new A = 2x - A
+ *
+ *     new B = 2x - B
+ *
+ *
+ * this point x is the sort of center of momentum. If, instead of bouncing, A
+ * and B just globbed together, x would be center of the new glob.
+ *
+ * x is the point where there's an equal amount of force coming in from both
+ * sides. ie the weighted average of the speeds of A and B.
+ *
+ * average force = (A force + B force) / total mass
+ *
+ * x.speed = (a.speed * a.mass + b.speed * b.mass) / (a.mass + b.mas)
+ *
+ * then we apply the formula above for calculating the new A and B.
+ *
+ *
+ *
+ *
+ * ******************  In 2 Dimensions  *****************
+ *
+ * OK, that's how we do it in 1D. Now we need to deal with 2D.
+ * 
+ * Imagine (or draw) the two balls just as they are bouncing off each other.
+ * Imagine drawing a line through the centers of the balls. The balls are
+ * exerting force on each other only along this axis. So if we rotate
+ * everything, we can do our earlier 1D math along this line.
+ *
+ * It doesn't matter what direction the balls are going in, they only exert
+ * force on each other along this line. What we will do is to compute the part
+ * of the balls' momentum that is going along this line, and bounce it according
+ * to our math above. The other part is unaffected by the bounce, and we can
+ * just leave it alone.
+ *
+ * To get this component of the balls' momentum, we can use the dot product.
+ *
+ *     dot(U, V) = length(U) * length(V) * cos(angle between U and V)
+ *
+ * If U is a length 1 vector, then dot(U, V) is the length of the component of V
+ * in the direction of U.  So the components of V are:
+ *
+ *     U * dot(U, V)      parallel to U
+ *
+ *     V - U * dot(U, V)  perpendicular to U
+ *
+ * To do the actual bounce, we compute the unit vector between the center of the
+ * two balls, compute the components of the balls' speeds along this vector (A
+ * and B), and then bounce them according to the math above:
+ *
+ *     new A = 2x - A
+ *
+ *     new B = 2x - B
+ *
+ * But we rewrite it in relative terms:
+ *
+ *     new A = A + 2(x-A)
+ *
+ *     new B = B + 2(x-B)
+ */
+
+void
+bounce(Sprite *a, Sprite *b)
+{
+	float x, y, n;  // (x, y) is unit vector from a to b.
+	float va, vb;   // va, vb are balls' speeds along (x, y)
+	float ma, mb;   // ma, mb are the balls' masses.
+	float vc;       // vc is the "center of momentum"
+
+	// (x, y) is unit vector pointing from A's center to B's center.
+	x = (b->x + b->w / 2) - (a->x + a->w / 2);
+	y = (b->y + b->h / 2) - (a->y + a->h / 2);
+	n = sqrt(x*x + y*y); x /= n; y /= n;
+
+	// velocities along (x, y)
+	va = x*a->dx + y*a->dy;
+	vb = x*b->dx + y*b->dy;
+	if(vb-va > 0) return;  // don't bounce if we're already moving away.
+
+	// get masses and compute "center" speed
+	ma = sprite_mass(a); mb = sprite_mass(b);
+	vc = (va*ma + vb*mb) / (ma+mb);
 
-	pmask = 0x80000000 >> (xoff&0x1f);
-	return r->mask[(yoff*r->mw) + (xoff>>5)] & pmask;
+	// bounce off the center speed.
+	a->dx += 2*x*(vc-va); a->dy += 2*y*(vc-va);
+	b->dx += 2*x*(vc-vb); b->dy += 2*y*(vc-vb);
 }