/********************************************************************************************** * * [physac] raylib physics module - Basic functions to apply physics to 2D objects * * Copyright (c) 2016 Victor Fisac and Ramon Santamaria * * This software is provided "as-is", without any express or implied warranty. In no event * will the authors be held liable for any damages arising from the use of this software. * * Permission is granted to anyone to use this software for any purpose, including commercial * applications, and to alter it and redistribute it freely, subject to the following restrictions: * * 1. The origin of this software must not be misrepresented; you must not claim that you * wrote the original software. If you use this software in a product, an acknowledgment * in the product documentation would be appreciated but is not required. * * 2. Altered source versions must be plainly marked as such, and must not be misrepresented * as being the original software. * * 3. This notice may not be removed or altered from any source distribution. * **********************************************************************************************/ //#define PHYSAC_STANDALONE // NOTE: To use the physics module as standalone lib, just uncomment this line #if defined(PHYSAC_STANDALONE) #include "physac.h" #else #include "raylib.h" #endif #include // Required for: malloc(), free() #include // Required for: cos(), sin(), abs(), fminf() //---------------------------------------------------------------------------------- // Defines and Macros //---------------------------------------------------------------------------------- #define MAX_PHYSIC_OBJECTS 256 // Maximum available physic object slots in objects pool #define PHYSICS_STEPS 450 // Physics update steps number (divided calculations in steps per frame) to get more accurately collisions detections #define PHYSICS_ACCURACY 0.0001f // Velocity subtract operations round filter (friction) #define PHYSICS_ERRORPERCENT 0.001f // Collision resolve position fix //---------------------------------------------------------------------------------- // Types and Structures Definition // NOTE: Below types are required for PHYSAC_STANDALONE usage //---------------------------------------------------------------------------------- // ... //---------------------------------------------------------------------------------- // Global Variables Definition //---------------------------------------------------------------------------------- static PhysicObject physicObjects[MAX_PHYSIC_OBJECTS]; // Physic objects pool static int physicObjectsCount; // Counts current enabled physic objects static Vector2 gravityForce; // Gravity force //---------------------------------------------------------------------------------- // Module specific Functions Declaration //---------------------------------------------------------------------------------- static float Vector2DotProduct(Vector2 v1, Vector2 v2); // Returns the dot product of two Vector2 static float Vector2Length(Vector2 v); // Returns the length of a Vector2 //---------------------------------------------------------------------------------- // Module Functions Definition //---------------------------------------------------------------------------------- // Initializes pointers array (just pointers, fixed size) void InitPhysics(Vector2 gravity) { // Initialize physics variables physicObjectsCount = 0; gravityForce = gravity; } // Update physic objects, calculating physic behaviours and collisions detection void UpdatePhysics() { // Reset all physic objects is grounded state for (int i = 0; i < physicObjectsCount; i++) physicObjects[i]->rigidbody.isGrounded = false; for (int steps = 0; steps < PHYSICS_STEPS; steps++) { for (int i = 0; i < physicObjectsCount; i++) { if (physicObjects[i]->enabled) { // Update physic behaviour if (physicObjects[i]->rigidbody.enabled) { // Apply friction to acceleration in X axis if (physicObjects[i]->rigidbody.acceleration.x > PHYSICS_ACCURACY) physicObjects[i]->rigidbody.acceleration.x -= physicObjects[i]->rigidbody.friction/PHYSICS_STEPS; else if (physicObjects[i]->rigidbody.acceleration.x < PHYSICS_ACCURACY) physicObjects[i]->rigidbody.acceleration.x += physicObjects[i]->rigidbody.friction/PHYSICS_STEPS; else physicObjects[i]->rigidbody.acceleration.x = 0.0f; // Apply friction to acceleration in Y axis if (physicObjects[i]->rigidbody.acceleration.y > PHYSICS_ACCURACY) physicObjects[i]->rigidbody.acceleration.y -= physicObjects[i]->rigidbody.friction/PHYSICS_STEPS; else if (physicObjects[i]->rigidbody.acceleration.y < PHYSICS_ACCURACY) physicObjects[i]->rigidbody.acceleration.y += physicObjects[i]->rigidbody.friction/PHYSICS_STEPS; else physicObjects[i]->rigidbody.acceleration.y = 0.0f; // Apply friction to velocity in X axis if (physicObjects[i]->rigidbody.velocity.x > PHYSICS_ACCURACY) physicObjects[i]->rigidbody.velocity.x -= physicObjects[i]->rigidbody.friction/PHYSICS_STEPS; else if (physicObjects[i]->rigidbody.velocity.x < PHYSICS_ACCURACY) physicObjects[i]->rigidbody.velocity.x += physicObjects[i]->rigidbody.friction/PHYSICS_STEPS; else physicObjects[i]->rigidbody.velocity.x = 0.0f; // Apply friction to velocity in Y axis if (physicObjects[i]->rigidbody.velocity.y > PHYSICS_ACCURACY) physicObjects[i]->rigidbody.velocity.y -= physicObjects[i]->rigidbody.friction/PHYSICS_STEPS; else if (physicObjects[i]->rigidbody.velocity.y < PHYSICS_ACCURACY) physicObjects[i]->rigidbody.velocity.y += physicObjects[i]->rigidbody.friction/PHYSICS_STEPS; else physicObjects[i]->rigidbody.velocity.y = 0.0f; // Apply gravity to velocity if (physicObjects[i]->rigidbody.applyGravity) { physicObjects[i]->rigidbody.velocity.x += gravityForce.x/PHYSICS_STEPS; physicObjects[i]->rigidbody.velocity.y += gravityForce.y/PHYSICS_STEPS; } // Apply acceleration to velocity physicObjects[i]->rigidbody.velocity.x += physicObjects[i]->rigidbody.acceleration.x/PHYSICS_STEPS; physicObjects[i]->rigidbody.velocity.y += physicObjects[i]->rigidbody.acceleration.y/PHYSICS_STEPS; // Apply velocity to position physicObjects[i]->transform.position.x += physicObjects[i]->rigidbody.velocity.x/PHYSICS_STEPS; physicObjects[i]->transform.position.y -= physicObjects[i]->rigidbody.velocity.y/PHYSICS_STEPS; } // Update collision detection if (physicObjects[i]->collider.enabled) { // Update collider bounds physicObjects[i]->collider.bounds = TransformToRectangle(physicObjects[i]->transform); // Check collision with other colliders for (int k = 0; k < physicObjectsCount; k++) { if (physicObjects[k]->collider.enabled && i != k) { // Resolve physic collision // NOTE: collision resolve is generic for all directions and conditions (no axis separated cases behaviours) // and it is separated in rigidbody attributes resolve (velocity changes by impulse) and position correction (position overlap) // 1. Calculate collision normal // ------------------------------------------------------------------------------------------------------------------------------------- // Define collision contact normal, direction and penetration depth Vector2 contactNormal = { 0.0f, 0.0f }; Vector2 direction = { 0.0f, 0.0f }; float penetrationDepth = 0.0f; switch (physicObjects[i]->collider.type) { case COLLIDER_RECTANGLE: { switch (physicObjects[k]->collider.type) { case COLLIDER_RECTANGLE: { // Check if colliders are overlapped if (CheckCollisionRecs(physicObjects[i]->collider.bounds, physicObjects[k]->collider.bounds)) { // Calculate direction vector from i to k direction.x = (physicObjects[k]->transform.position.x + physicObjects[k]->transform.scale.x/2) - (physicObjects[i]->transform.position.x + physicObjects[i]->transform.scale.x/2); direction.y = (physicObjects[k]->transform.position.y + physicObjects[k]->transform.scale.y/2) - (physicObjects[i]->transform.position.y + physicObjects[i]->transform.scale.y/2); // Define overlapping and penetration attributes Vector2 overlap; // Calculate overlap on X axis overlap.x = (physicObjects[i]->transform.scale.x + physicObjects[k]->transform.scale.x)/2 - abs(direction.x); // SAT test on X axis if (overlap.x > 0.0f) { // Calculate overlap on Y axis overlap.y = (physicObjects[i]->transform.scale.y + physicObjects[k]->transform.scale.y)/2 - abs(direction.y); // SAT test on Y axis if (overlap.y > 0.0f) { // Find out which axis is axis of least penetration if (overlap.y > overlap.x) { // Point towards k knowing that direction points from i to k if (direction.x < 0.0f) contactNormal = (Vector2){ -1.0f, 0.0f }; else contactNormal = (Vector2){ 1.0f, 0.0f }; // Update penetration depth for position correction penetrationDepth = overlap.x; } else { // Point towards k knowing that direction points from i to k if (direction.y < 0.0f) contactNormal = (Vector2){ 0.0f, 1.0f }; else contactNormal = (Vector2){ 0.0f, -1.0f }; // Update penetration depth for position correction penetrationDepth = overlap.y; } } } } } break; case COLLIDER_CIRCLE: { if (CheckCollisionCircleRec(physicObjects[k]->transform.position, physicObjects[k]->collider.radius, physicObjects[i]->collider.bounds)) { // Calculate direction vector between circles direction.x = physicObjects[k]->transform.position.x - physicObjects[i]->transform.position.x + physicObjects[i]->transform.scale.x/2; direction.y = physicObjects[k]->transform.position.y - physicObjects[i]->transform.position.y + physicObjects[i]->transform.scale.y/2; // Calculate closest point on rectangle to circle Vector2 closestPoint = { 0.0f, 0.0f }; if (direction.x > 0.0f) closestPoint.x = physicObjects[i]->collider.bounds.x + physicObjects[i]->collider.bounds.width; else closestPoint.x = physicObjects[i]->collider.bounds.x; if (direction.y > 0.0f) closestPoint.y = physicObjects[i]->collider.bounds.y + physicObjects[i]->collider.bounds.height; else closestPoint.y = physicObjects[i]->collider.bounds.y; // Check if the closest point is inside the circle if (CheckCollisionPointCircle(closestPoint, physicObjects[k]->transform.position, physicObjects[k]->collider.radius)) { // Recalculate direction based on closest point position direction.x = physicObjects[k]->transform.position.x - closestPoint.x; direction.y = physicObjects[k]->transform.position.y - closestPoint.y; float distance = Vector2Length(direction); // Calculate final contact normal contactNormal.x = direction.x/distance; contactNormal.y = -direction.y/distance; // Calculate penetration depth penetrationDepth = physicObjects[k]->collider.radius - distance; } else { if (abs(direction.y) < abs(direction.x)) { // Calculate final contact normal if (direction.y > 0.0f) { contactNormal = (Vector2){ 0.0f, -1.0f }; penetrationDepth = fabs(physicObjects[i]->collider.bounds.y - physicObjects[k]->transform.position.y - physicObjects[k]->collider.radius); } else { contactNormal = (Vector2){ 0.0f, 1.0f }; penetrationDepth = fabs(physicObjects[i]->collider.bounds.y - physicObjects[k]->transform.position.y + physicObjects[k]->collider.radius); } } else { // Calculate final contact normal if (direction.x > 0.0f) { contactNormal = (Vector2){ 1.0f, 0.0f }; penetrationDepth = fabs(physicObjects[k]->transform.position.x + physicObjects[k]->collider.radius - physicObjects[i]->collider.bounds.x); } else { contactNormal = (Vector2){ -1.0f, 0.0f }; penetrationDepth = fabs(physicObjects[i]->collider.bounds.x + physicObjects[i]->collider.bounds.width - physicObjects[k]->transform.position.x - physicObjects[k]->collider.radius); } } } } } break; } } break; case COLLIDER_CIRCLE: { switch (physicObjects[k]->collider.type) { case COLLIDER_RECTANGLE: { if (CheckCollisionCircleRec(physicObjects[i]->transform.position, physicObjects[i]->collider.radius, physicObjects[k]->collider.bounds)) { // Calculate direction vector between circles direction.x = physicObjects[k]->transform.position.x + physicObjects[i]->transform.scale.x/2 - physicObjects[i]->transform.position.x; direction.y = physicObjects[k]->transform.position.y + physicObjects[i]->transform.scale.y/2 - physicObjects[i]->transform.position.y; // Calculate closest point on rectangle to circle Vector2 closestPoint = { 0.0f, 0.0f }; if (direction.x > 0.0f) closestPoint.x = physicObjects[k]->collider.bounds.x + physicObjects[k]->collider.bounds.width; else closestPoint.x = physicObjects[k]->collider.bounds.x; if (direction.y > 0.0f) closestPoint.y = physicObjects[k]->collider.bounds.y + physicObjects[k]->collider.bounds.height; else closestPoint.y = physicObjects[k]->collider.bounds.y; // Check if the closest point is inside the circle if (CheckCollisionPointCircle(closestPoint, physicObjects[i]->transform.position, physicObjects[i]->collider.radius)) { // Recalculate direction based on closest point position direction.x = physicObjects[i]->transform.position.x - closestPoint.x; direction.y = physicObjects[i]->transform.position.y - closestPoint.y; float distance = Vector2Length(direction); // Calculate final contact normal contactNormal.x = direction.x/distance; contactNormal.y = -direction.y/distance; // Calculate penetration depth penetrationDepth = physicObjects[k]->collider.radius - distance; } else { if (abs(direction.y) < abs(direction.x)) { // Calculate final contact normal if (direction.y > 0.0f) { contactNormal = (Vector2){ 0.0f, -1.0f }; penetrationDepth = fabs(physicObjects[k]->collider.bounds.y - physicObjects[i]->transform.position.y - physicObjects[i]->collider.radius); } else { contactNormal = (Vector2){ 0.0f, 1.0f }; penetrationDepth = fabs(physicObjects[k]->collider.bounds.y - physicObjects[i]->transform.position.y + physicObjects[i]->collider.radius); } } else { // Calculate final contact normal and penetration depth if (direction.x > 0.0f) { contactNormal = (Vector2){ 1.0f, 0.0f }; penetrationDepth = fabs(physicObjects[i]->transform.position.x + physicObjects[i]->collider.radius - physicObjects[k]->collider.bounds.x); } else { contactNormal = (Vector2){ -1.0f, 0.0f }; penetrationDepth = fabs(physicObjects[k]->collider.bounds.x + physicObjects[k]->collider.bounds.width - physicObjects[i]->transform.position.x - physicObjects[i]->collider.radius); } } } } } break; case COLLIDER_CIRCLE: { // Check if colliders are overlapped if (CheckCollisionCircles(physicObjects[i]->transform.position, physicObjects[i]->collider.radius, physicObjects[k]->transform.position, physicObjects[k]->collider.radius)) { // Calculate direction vector between circles direction.x = physicObjects[k]->transform.position.x - physicObjects[i]->transform.position.x; direction.y = physicObjects[k]->transform.position.y - physicObjects[i]->transform.position.y; // Calculate distance between circles float distance = Vector2Length(direction); // Check if circles are not completely overlapped if (distance != 0.0f) { // Calculate contact normal direction (Y axis needs to be flipped) contactNormal.x = direction.x/distance; contactNormal.y = -direction.y/distance; } else contactNormal = (Vector2){ 1.0f, 0.0f }; // Choose random (but consistent) values } } break; default: break; } } break; default: break; } // Update rigidbody grounded state if (physicObjects[i]->rigidbody.enabled) { if (contactNormal.y < 0.0f) physicObjects[i]->rigidbody.isGrounded = true; } // 2. Calculate collision impulse // ------------------------------------------------------------------------------------------------------------------------------------- // Calculate relative velocity Vector2 relVelocity = { 0.0f, 0.0f }; relVelocity.x = physicObjects[k]->rigidbody.velocity.x - physicObjects[i]->rigidbody.velocity.x; relVelocity.y = physicObjects[k]->rigidbody.velocity.y - physicObjects[i]->rigidbody.velocity.y; // Calculate relative velocity in terms of the normal direction float velAlongNormal = Vector2DotProduct(relVelocity, contactNormal); // Dot not resolve if velocities are separating if (velAlongNormal <= 0.0f) { // Calculate minimum bounciness value from both objects float e = fminf(physicObjects[i]->rigidbody.bounciness, physicObjects[k]->rigidbody.bounciness); // Calculate impulse scalar value float j = -(1.0f + e)*velAlongNormal; j /= 1.0f/physicObjects[i]->rigidbody.mass + 1.0f/physicObjects[k]->rigidbody.mass; // Calculate final impulse vector Vector2 impulse = { j*contactNormal.x, j*contactNormal.y }; // Calculate collision mass ration float massSum = physicObjects[i]->rigidbody.mass + physicObjects[k]->rigidbody.mass; float ratio = 0.0f; // Apply impulse to current rigidbodies velocities if they are enabled if (physicObjects[i]->rigidbody.enabled) { // Calculate inverted mass ration ratio = physicObjects[i]->rigidbody.mass/massSum; // Apply impulse direction to velocity physicObjects[i]->rigidbody.velocity.x -= impulse.x*ratio*(1.0f+physicObjects[i]->rigidbody.bounciness); physicObjects[i]->rigidbody.velocity.y -= impulse.y*ratio*(1.0f+physicObjects[i]->rigidbody.bounciness); } if (physicObjects[k]->rigidbody.enabled) { // Calculate inverted mass ration ratio = physicObjects[k]->rigidbody.mass/massSum; // Apply impulse direction to velocity physicObjects[k]->rigidbody.velocity.x += impulse.x*ratio*(1.0f+physicObjects[i]->rigidbody.bounciness); physicObjects[k]->rigidbody.velocity.y += impulse.y*ratio*(1.0f+physicObjects[i]->rigidbody.bounciness); } // 3. Correct colliders overlaping (transform position) // --------------------------------------------------------------------------------------------------------------------------------- // Calculate transform position penetration correction Vector2 posCorrection; posCorrection.x = penetrationDepth/((1.0f/physicObjects[i]->rigidbody.mass) + (1.0f/physicObjects[k]->rigidbody.mass))*PHYSICS_ERRORPERCENT*contactNormal.x; posCorrection.y = penetrationDepth/((1.0f/physicObjects[i]->rigidbody.mass) + (1.0f/physicObjects[k]->rigidbody.mass))*PHYSICS_ERRORPERCENT*contactNormal.y; // Fix transform positions if (physicObjects[i]->rigidbody.enabled) { // Fix physic objects transform position physicObjects[i]->transform.position.x -= 1.0f/physicObjects[i]->rigidbody.mass*posCorrection.x; physicObjects[i]->transform.position.y += 1.0f/physicObjects[i]->rigidbody.mass*posCorrection.y; // Update collider bounds physicObjects[i]->collider.bounds = TransformToRectangle(physicObjects[i]->transform); if (physicObjects[k]->rigidbody.enabled) { // Fix physic objects transform position physicObjects[k]->transform.position.x += 1.0f/physicObjects[k]->rigidbody.mass*posCorrection.x; physicObjects[k]->transform.position.y -= 1.0f/physicObjects[k]->rigidbody.mass*posCorrection.y; // Update collider bounds physicObjects[k]->collider.bounds = TransformToRectangle(physicObjects[k]->transform); } } } } } } } } } } // Unitialize all physic objects and empty the objects pool void ClosePhysics() { // Free all dynamic memory allocations for (int i = 0; i < physicObjectsCount; i++) free(physicObjects[i]); // Reset enabled physic objects count physicObjectsCount = 0; } // Create a new physic object dinamically, initialize it and add to pool PhysicObject CreatePhysicObject(Vector2 position, float rotation, Vector2 scale) { // Allocate dynamic memory PhysicObject obj = (PhysicObject)malloc(sizeof(PhysicObjectData)); // Initialize physic object values with generic values obj->id = physicObjectsCount; obj->enabled = true; obj->transform = (Transform){ (Vector2){ position.x - scale.x/2, position.y - scale.y/2 }, rotation, scale }; obj->rigidbody.enabled = false; obj->rigidbody.mass = 1.0f; obj->rigidbody.acceleration = (Vector2){ 0.0f, 0.0f }; obj->rigidbody.velocity = (Vector2){ 0.0f, 0.0f }; obj->rigidbody.applyGravity = false; obj->rigidbody.isGrounded = false; obj->rigidbody.friction = 0.0f; obj->rigidbody.bounciness = 0.0f; obj->collider.enabled = true; obj->collider.type = COLLIDER_RECTANGLE; obj->collider.bounds = TransformToRectangle(obj->transform); obj->collider.radius = 0.0f; // Add new physic object to the pointers array physicObjects[physicObjectsCount] = obj; // Increase enabled physic objects count physicObjectsCount++; return obj; } // Destroy a specific physic object and take it out of the list void DestroyPhysicObject(PhysicObject pObj) { // Free dynamic memory allocation free(physicObjects[pObj->id]); // Remove *obj from the pointers array for (int i = pObj->id; i < physicObjectsCount; i++) { // Resort all the following pointers of the array if ((i + 1) < physicObjectsCount) { physicObjects[i] = physicObjects[i + 1]; physicObjects[i]->id = physicObjects[i + 1]->id; } else free(physicObjects[i]); } // Decrease enabled physic objects count physicObjectsCount--; } // Apply directional force to a physic object void ApplyForce(PhysicObject pObj, Vector2 force) { if (pObj->rigidbody.enabled) { pObj->rigidbody.velocity.x += force.x/pObj->rigidbody.mass; pObj->rigidbody.velocity.y += force.y/pObj->rigidbody.mass; } } // Apply radial force to all physic objects in range void ApplyForceAtPosition(Vector2 position, float force, float radius) { for (int i = 0; i < physicObjectsCount; i++) { if (physicObjects[i]->rigidbody.enabled) { // Calculate direction and distance between force and physic object pposition Vector2 distance = (Vector2){ physicObjects[i]->transform.position.x - position.x, physicObjects[i]->transform.position.y - position.y }; if (physicObjects[i]->collider.type == COLLIDER_RECTANGLE) { distance.x += physicObjects[i]->transform.scale.x/2; distance.y += physicObjects[i]->transform.scale.y/2; } float distanceLength = Vector2Length(distance); // Check if physic object is in force range if (distanceLength <= radius) { // Normalize force direction distance.x /= distanceLength; distance.y /= -distanceLength; // Calculate final force Vector2 finalForce = { distance.x*force, distance.y*force }; // Apply force to the physic object ApplyForce(physicObjects[i], finalForce); } } } } // Convert Transform data type to Rectangle (position and scale) Rectangle TransformToRectangle(Transform transform) { return (Rectangle){transform.position.x, transform.position.y, transform.scale.x, transform.scale.y}; } //---------------------------------------------------------------------------------- // Module specific Functions Definition //---------------------------------------------------------------------------------- // Returns the dot product of two Vector2 static float Vector2DotProduct(Vector2 v1, Vector2 v2) { float result; result = v1.x*v2.x + v1.y*v2.y; return result; } static float Vector2Length(Vector2 v) { float result; result = sqrt(v.x*v.x + v.y*v.y); return result; }