/* 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 <string.h> #include "chipmunk/chipmunk.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(cpShapePointQuery(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 = cpPolyShapeGetCount(shape); count = (count > MAX_VERTEXES_PER_VORONOI ? MAX_VERTEXES_PER_VORONOI : count); for(int i=0; i<count; i++){ ping[i] = cpBodyLocalToWorld(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) && cpShapePointQuery(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, 0.0f)*DENSITY; cpFloat moment = cpMomentForPoly(mass, count, ping, cpvneg(centroid), 0.0f); cpBody *new_body = cpSpaceAddBody(space, cpBodyNew(mass, moment)); cpBodySetPosition(new_body, centroid); cpBodySetVelocity(new_body, cpBodyGetVelocityAtWorldPoint(body, centroid)); cpBodySetAngularVelocity(new_body, cpBodyGetAngularVelocity(body)); cpTransform transform = cpTransformTranslate(cpvneg(centroid)); cpShape *new_shape = cpSpaceAddShape(space, cpPolyShapeNew(new_body, count, ping, transform, 0.0)); // 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, cpShapeGetBody(shape)); cpBB bb = cpShapeGetBB(shape); int width = (int)((bb.r - bb.l)/cellSize) + 1; int height = (int)((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(cpShapePointQuery(shape, cell, NULL) < 0.0f){ ShatterCell(space, shape, cell, i, j, &context); } } } cpBodyFree(cpShapeGetBody(shape)); cpShapeFree(shape); } static void update(cpSpace *space, double dt) { cpSpaceStep(space, dt); if(ChipmunkDemoRightDown){ cpPointQueryInfo info; if(cpSpacePointQueryNearest(space, ChipmunkDemoMouse, 0, GRAB_FILTER, &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, (cpShape *)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); cpShapeSetFilter(shape, NOT_GRABBABLE_FILTER); 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, 0.0)); cpShapeSetFriction(shape, 0.6f); return space; } static void destroy(cpSpace *space) { ChipmunkDemoFreeSpaceChildren(space); cpSpaceFree(space); } //ChipmunkDemo Shatter = { // "Shatter.", // 1.0f/60.0f, // init, // update, // ChipmunkDemoDefaultDrawImpl, // destroy, //};