#include #include void readn(byte *dst, unsigned int addr, int c) { GD.__start(addr); while (c--) *dst++ = SPI.transfer(0); GD.__end(); } #define NBALLS 80 static byte coll[NBALLS]; static void load_coll() { while (GD.rd(VBLANK) == 0) // Wait until vblank ; while (GD.rd(VBLANK) == 1) // Wait until display ; while (GD.rd(VBLANK) == 0) // Wait until vblank ; readn(coll, COLLISION, NBALLS); } struct ball { int x, y; char vx, vy; byte lasthit; }; static struct ball balls[NBALLS]; #include "stone_wall_texture.h" // texture from 3dmd.net project #include "sphere.h" static void plot_balls() { byte i; for (i = 0; i < NBALLS; i++) GD.sprite(i, balls[i].x >> 4, balls[i].y >> 4, 0, 0, 0); } // Place all balls so that none collide. Do this by placing all at // random, then moving until there are no collisions static byte anycolliding() { plot_balls(); load_coll(); byte i; for (i = 0; i < NBALLS; i++) if (coll[i] != 0xff) return 1; return 0; } static void place_balls() { byte i; for (i = 0; i < NBALLS; i++) { balls[i].x = (2 + random(380)) << 4; balls[i].y = (2 + random(280)) << 4; balls[i].vx = random(-128,127); balls[i].vy = random(-128,127); balls[i].lasthit = 255; } while (anycolliding()) { for (i = 0; i < NBALLS; i++) { if (coll[i] != 0xff) { balls[i].x = (2 + random(380)) << 4; balls[i].y = (2 + random(280)) << 4; } } } } void setup() { int i; GD.begin(); GD.wr(JK_MODE, 0); GD.copy(RAM_CHR, stone_wall_texture_chr, sizeof(stone_wall_texture_chr)); GD.copy(RAM_PAL, stone_wall_texture_pal, sizeof(stone_wall_texture_pal)); for (i = 0; i < 4096; i++) GD.wr(RAM_PIC + i, (i & 15) + ((i >> 6) << 4)); GD.copy(RAM_SPRIMG, sphere_img, sizeof(sphere_img)); GD.copy(RAM_SPRPAL, sphere_pal, sizeof(sphere_pal)); for (i = 0; i < 256; i++) GD.sprite(i, 400, 400, 0, 0, 0); place_balls(); } float dot(float x1, float y1, float x2, float y2) { return (x1 * x2) + (y1 * y2); } // Collide ball a with ball b, compute new velocities. // Algorithm from // http://stackoverflow.com/questions/345838/ball-to-ball-collision-detection-and-handling void collide(struct ball *a, struct ball *b) { float collision_x, collision_y; collision_x = a->x - b->x; collision_y = a->y - b->y; float distance = sqrt(collision_x * collision_x + collision_y * collision_y); float rdistance = 1.0 / distance; collision_x *= rdistance; collision_y *= rdistance; float aci = dot(a->vx, a->vy, collision_x, collision_y); float bci = dot(b->vx, b->vy, collision_x, collision_y); float acf = bci; float bcf = aci; a->vx += int((acf - aci) * collision_x); a->vy += int((acf - aci) * collision_y); b->vx += int((bcf - bci) * collision_x); b->vy += int((bcf - bci) * collision_y); } #define LWALL (0 << 4) #define RWALL (384 << 4) #define TWALL (0 << 4) #define BWALL (284 << 4) static int timer; void loop() { int i; plot_balls(); load_coll(); struct ball *pb; for (i = NBALLS, pb = balls; i; pb++, i--) { if ((pb->x <= LWALL)) { pb->x = LWALL; pb->vx = -pb->vx; } if ((pb->x >= RWALL)) { pb->x = RWALL; pb->vx = -pb->vx; } if ((pb->y <= TWALL)) { pb->y = TWALL; pb->vy = -pb->vy; } if ((pb->y >= BWALL)) { pb->y = BWALL; pb->vy = -pb->vy; } } for (i = 1; i < NBALLS; i++) { byte other = coll[i]; if ((balls[i].lasthit != other) && other != 0xff) { collide(&balls[i], &balls[other]); } balls[i].lasthit = other; } for (i = NBALLS, pb = balls; i; pb++, i--) { pb->x += pb->vx; pb->y += pb->vy; } if (++timer == 2000) { place_balls(); delay(1000); timer = 0; } }