/* Copyright (c) 2007 Scott Lembcke
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#include "chipmunk.h"
#include "constraints/util.h"
#include "ChipmunkDemo.h"
#define DENSITY (1.0/10000.0)
#define MAX_VERTEXES_PER_VORONOI 16
struct WorleyContex {
uint32_t seed;
cpFloat cellSize;
int width, height;
cpBB bb;
cpVect focus;
};
static inline cpVect
HashVect(uint32_t x, uint32_t y, uint32_t seed)
{
// cpFloat border = 0.21f;
cpFloat border = 0.05f;
uint32_t h = (x*1640531513 ^ y*2654435789) + seed;
return cpv(
cpflerp(border, 1.0f - border, (cpFloat)( h & 0xFFFF)/(cpFloat)0xFFFF),
cpflerp(border, 1.0f - border, (cpFloat)((h>>16) & 0xFFFF)/(cpFloat)0xFFFF)
);
}
static cpVect
WorleyPoint(int i, int j, struct WorleyContex *context)
{
cpFloat size = context->cellSize;
int width = context->width;
int height = context->height;
cpBB bb = context->bb;
// cpVect fv = cpv(0.5, 0.5);
cpVect fv = HashVect(i, j, context->seed);
return cpv(
cpflerp(bb.l, bb.r, 0.5f) + size*(i + fv.x - width*0.5f),
cpflerp(bb.b, bb.t, 0.5f) + size*(j + fv.y - height*0.5f)
);
}
static int
ClipCell(cpShape *shape, cpVect center, int i, int j, struct WorleyContex *context, cpVect *verts, cpVect *clipped, int count)
{
cpVect other = WorleyPoint(i, j, context);
// printf(" other %dx%d: (% 5.2f, % 5.2f) ", i, j, other.x, other.y);
if(cpShapeNearestPointQuery(shape, other, NULL) > 0.0f){
// printf("excluded\n");
memcpy(clipped, verts, count*sizeof(cpVect));
return count;
} else {
// printf("clipped\n");
}
cpVect n = cpvsub(other, center);
cpFloat dist = cpvdot(n, cpvlerp(center, other, 0.5f));
int clipped_count = 0;
for(int j=0, i=count-1; j<count; i=j, j++){
cpVect a = verts[i];
cpFloat a_dist = cpvdot(a, n) - dist;
if(a_dist <= 0.0){
clipped[clipped_count] = a;
clipped_count++;
}
cpVect b = verts[j];
cpFloat b_dist = cpvdot(b, n) - dist;
if(a_dist*b_dist < 0.0f){
cpFloat t = cpfabs(a_dist)/(cpfabs(a_dist) + cpfabs(b_dist));
clipped[clipped_count] = cpvlerp(a, b, t);
clipped_count++;
}
}
return clipped_count;
}
static void
ShatterCell(cpSpace *space, cpShape *shape, cpVect cell, int cell_i, int cell_j, struct WorleyContex *context)
{
// printf("cell %dx%d: (% 5.2f, % 5.2f)\n", cell_i, cell_j, cell.x, cell.y);
cpBody *body = cpShapeGetBody(shape);
cpVect *ping = (cpVect *)alloca(MAX_VERTEXES_PER_VORONOI*sizeof(cpVect));
cpVect *pong = (cpVect *)alloca(MAX_VERTEXES_PER_VORONOI*sizeof(cpVect));
int count = cpPolyShapeGetNumVerts(shape);
count = (count > MAX_VERTEXES_PER_VORONOI ? MAX_VERTEXES_PER_VORONOI : count);
for(int i=0; i<count; i++){
ping[i] = cpBodyLocal2World(body, cpPolyShapeGetVert(shape, i));
}
for(int i=0; i<context->width; i++){
for(int j=0; j<context->height; j++){
if(
!(i == cell_i && j == cell_j) &&
cpShapeNearestPointQuery(shape, cell, NULL) < 0.0f
){
count = ClipCell(shape, cell, i, j, context, ping, pong, count);
memcpy(ping, pong, count*sizeof(cpVect));
}
}
}
cpVect centroid = cpCentroidForPoly(count, ping);
cpFloat mass = cpAreaForPoly(count, ping)*DENSITY;
cpFloat moment = cpMomentForPoly(mass, count, ping, cpvneg(centroid));
cpBody *new_body = cpSpaceAddBody(space, cpBodyNew(mass, moment));
cpBodySetPos(new_body, centroid);
cpBodySetVel(new_body, cpBodyGetVelAtWorldPoint(body, centroid));
cpBodySetAngVel(new_body, cpBodyGetAngVel(body));
cpShape *new_shape = cpSpaceAddShape(space, cpPolyShapeNew(new_body, count, ping, cpvneg(centroid)));
// Copy whatever properties you have set on the original shape that are important
cpShapeSetFriction(new_shape, cpShapeGetFriction(shape));
}
static void
ShatterShape(cpSpace *space, cpShape *shape, cpFloat cellSize, cpVect focus)
{
cpSpaceRemoveShape(space, shape);
cpSpaceRemoveBody(space, shape->body);
cpBB bb = cpShapeGetBB(shape);
int width = (bb.r - bb.l)/cellSize + 1;
int height = (bb.t - bb.b)/cellSize + 1;
// printf("Splitting as %dx%d\n", width, height);
struct WorleyContex context = {rand(), cellSize, width, height, bb, focus};
for(int i=0; i<context.width; i++){
for(int j=0; j<context.height; j++){
cpVect cell = WorleyPoint(i, j, &context);
if(cpShapeNearestPointQuery(shape, cell, NULL) < 0.0f){
ShatterCell(space, shape, cell, i, j, &context);
}
}
}
cpBodyFree(shape->body);
cpShapeFree(shape);
}
static void
update(cpSpace *space)
{
int steps = 1;
cpFloat dt = 1.0f/60.0f/(cpFloat)steps;
for(int i=0; i<steps; i++){
cpSpaceStep(space, dt);
}
if(ChipmunkDemoRightDown){
cpNearestPointQueryInfo info;
if(cpSpaceNearestPointQueryNearest(space, ChipmunkDemoMouse, 0, GRABABLE_MASK_BIT, CP_NO_GROUP, &info)){
cpBB bb = cpShapeGetBB(info.shape);
cpFloat cell_size = cpfmax(bb.r - bb.l, bb.t - bb.b)/5.0f;
if(cell_size > 5.0f){
ShatterShape(space, info.shape, cell_size, ChipmunkDemoMouse);
} else {
printf("Too small to splinter %f\n", cell_size);
}
}
}
}
static cpSpace *
init(void)
{
ChipmunkDemoMessageString = "Right click something to shatter it.";
cpSpace *space = cpSpaceNew();
cpSpaceSetIterations(space, 30);
cpSpaceSetGravity(space, cpv(0, -500));
cpSpaceSetSleepTimeThreshold(space, 0.5f);
cpSpaceSetCollisionSlop(space, 0.5f);
cpBody *body, *staticBody = cpSpaceGetStaticBody(space);
cpShape *shape;
// Create segments around the edge of the screen.
shape = cpSpaceAddShape(space, cpSegmentShapeNew(staticBody, cpv(-1000, -240), cpv( 1000, -240), 0.0f));
cpShapeSetElasticity(shape, 1.0f);
cpShapeSetFriction(shape, 1.0f);
cpShapeSetLayers(shape, NOT_GRABABLE_MASK);
cpFloat width = 200.0f;
cpFloat height = 200.0f;
cpFloat mass = width*height*DENSITY;
cpFloat moment = cpMomentForBox(mass, width, height);
body = cpSpaceAddBody(space, cpBodyNew(mass, moment));
shape = cpSpaceAddShape(space, cpBoxShapeNew(body, width, height));
cpShapeSetFriction(shape, 0.6f);
return space;
}
static void
destroy(cpSpace *space)
{
ChipmunkDemoFreeSpaceChildren(space);
cpSpaceFree(space);
}
ChipmunkDemo Shatter = {
"Shatter.",
init,
update,
ChipmunkDemoDefaultDrawImpl,
destroy,
};
