ref: 997fe9a10272cd9c3a5f128213e64008ee663078
dir: /SDL_Examples/include/chadphys.h/
#ifndef CHAD_PHYS_H #define CHAD_PHYS_H #ifdef CHAD_PHYS_IMPL #define CHAD_MATH_IMPL #endif #include "3dMath.h" typedef struct { aabb shape; //c.d[3] is sphere radius. //if it's zero or less, it's not a sphere, it's a box f_ mass; //0 means kinematic, or static. Defaults to zero. f_ bounciness; //default 0, put portion of displacement into velocity. f_ airfriction; //default 1, multiplied by velocity every time timestep. f_ friction; //default 0.1 vec3 r; //Rotation, Used for rendering only vec3 v; //velocity vec3 a; //Body specific acceleration, combined with gravity void* d; //User defined pointer. } phys_body; typedef struct{ phys_body* abodies; //mass non-zero phys_body* sbodies; //mass zero uint nabodies; //number of abodies uint nsbodies; //number of sbodies vec3 g; //gravity f_ ms; //max speed } phys_world; void stepPhysWorld(phys_world* world); void resolveBodies(phys_body* a, phys_body* b); void initPhysWorld(phys_world* world); //inits to NULL void initPhysBody(phys_body* body); //inits to defaults specified above. #ifdef CHAD_PHYS_IMPL //TODO: implement functions void initPhysBody(phys_body* body){ body->shape = (aabb){ .c=(vec4){.d[0] = 0,.d[1] = 0,.d[2] = 0,.d[3] = 0}, .e=(vec3){.d[0] = 0,.d[1] = 0,.d[2] = 0} }; body->mass = 0; body->bounciness = 0; body->friction = 0.1; body->airfriction = 1.0; body->a = (vec3){.d[0] = 0,.d[1] = 0,.d[2] = 0}; body->r = (vec3){.d[0] = 0,.d[1] = 0,.d[2] = 0}; body->d = NULL; } //Check for and, if necessary, resolve colliding bodies. void resolveBodies(phys_body* a, phys_body* b){ if(a->mass <= 0 && b->mass <= 0) return; //Perform a preliminary check. Do we even have to do anything? //Check if the two bodies are colliding. vec4 penvec = (vec4){ .d[0]=0, .d[1]=0, .d[2]=0, .d[3]=0 }; if(a->shape.c.d[3] > 0 && b->shape.c.d[3] > 0) //Both Spheres! { penvec = spherevsphere(a->shape.c, b->shape.c); } else if(a->shape.c.d[3] <= 0 && b->shape.c.d[3] <= 0) //Both boxes! { penvec = boxvbox(a->shape,b->shape); } else if (a->shape.c.d[3] > 0 && b->shape.c.d[3] <= 0) //a is a sphere, b is a box { penvec = spherevaabb(a->shape.c,b->shape); } else if (a->shape.c.d[3] <= 0 && b->shape.c.d[3] > 0){ //a is a box, b is a sphere penvec = spherevaabb(b->shape.c,a->shape); penvec.d[0] *= -1; penvec.d[1] *= -1; penvec.d[2] *= -1; } else { puts("\nInvalid configuration. Error.\n"); } if(penvec.d[3] <= 0) return; //No penetration detected, or invalid configuration. //We now have the penetration vector. There is a penetration. //determine how much each should be displaced by. //The penvec points INTO A and is of length penvec.d[3] float bdisplacefactor = a->mass / (a->mass + b->mass), adisplacefactor = b->mass / (a->mass + b->mass); if(!(a->mass > 0)) {adisplacefactor = 0; bdisplacefactor = 1;} if(!(b->mass > 0)) {bdisplacefactor = 0; adisplacefactor = 1;} vec3 avel = a->v; vec3 bvel = b->v; vec3 arelvel = subv3(a->v, b->v); vec3 brelvel = subv3(b->v, a->v); if(a->mass > 0){ vec4 displacea = scalev4(-adisplacefactor, penvec); //Note: SSE will accelerate a 4-lane multiply better than 3. a->shape.c.d[0] += displacea.d[0]; a->shape.c.d[1] += displacea.d[1]; a->shape.c.d[2] += displacea.d[2]; a->v = addv3(scalev3(1.0-a->friction, arelvel),bvel); //Apply friction! a->v = addv3(a->v, scalev3( a->bounciness, downv4(displacea) ) ); } if(b->mass > 0){ vec4 displaceb = scalev4(bdisplacefactor, penvec); //The vector returned by collision functions points INTO B! b->shape.c.d[0] += displaceb.d[0]; b->shape.c.d[1] += displaceb.d[1]; b->shape.c.d[2] += displaceb.d[2]; b->v = addv3(scalev3(1.0 - b->friction, brelvel),avel); b->v = addv3(b->v, scalev3( b->bounciness, downv4(displaceb) ) ); } } #endif #endif