void ofApp::setupScene(int width, int height)
{
/* setup camera */
double aspectRatio = static_cast<double>(width) / height;
ofVec3f topLeft (-CAMERA_SIZE * aspectRatio, CAMERA_SIZE, 0.0);
ofVec3f botLeft (-CAMERA_SIZE * aspectRatio, -CAMERA_SIZE, 0.0);
ofVec3f botRight( CAMERA_SIZE * aspectRatio, -CAMERA_SIZE, 0.0);
cam = OffAxisCamera(topLeft, botLeft, botRight);
cam.setPosition(ofVec3f(0.0, 0.0, 50.0f));
/* calculate grid box dimension */
ofVec3f camWidthVec = botRight - botLeft;
double camWidth = camWidthVec.length();
gridBox = GridBox(ofVec3f(-CAMERA_SIZE * aspectRatio, -CAMERA_SIZE, 0.0f),
camWidth, camWidth / aspectRatio, 8.0f);
}
MTV Collision::getCollision(const sf::Sprite& object1,Entity::ENTITY_SHAPE shape1,const sf::Sprite& object2,Entity::ENTITY_SHAPE shape2){
//Use Separating Axis Theorem to determine whether two objects are overlapping
//See documentation for full explanation of this algorithm
//Get the oriented bounding box in world coordinates (includes rotation) of objects
OBB obb1 = getOBB(object1);
OBB obb2 = getOBB(object2);
float rot = object1.getRotation();
double overlap = LONG_MAX;
maths::Vector2 smallest(0,0);
std::vector<maths::Vector2> axis1;
std::vector<maths::Vector2> axis2;
maths::Vector2 circleCentre1;
maths::Vector2 circleCentre2;
sf::FloatRect gbounds1 = object1.getGlobalBounds();
sf::FloatRect gbounds2 = object2.getGlobalBounds();
//Find all the axes to check using SAT based on shapes of objects
//Works with squares/rectangles or circles
//Rectangles only need 2 axes because they have 2 sets of parallel lines
if(shape1 == Entity::SHAPE_CIRCLE && shape2 == Entity::SHAPE_CIRCLE){
//If both shapes are circles, the only axis needed is the axis between centres of circles
circleCentre1 = maths::Vector2(gbounds1.left + gbounds1.width / 2, gbounds1.top + gbounds1.height / 2);
circleCentre2 = maths::Vector2(gbounds2.left + gbounds2.width / 2, gbounds2.top + gbounds2.height / 2);
axis1.push_back(maths::Vector2(circleCentre1 - circleCentre2).normalise());
}else if(shape1 != shape2){ //if one shape is circle and one shape is rectangle
maths::Vector2 circleCentre;
sf::FloatRect squareRect;
float rotation;
//First get the unrotated bounding box and centre of the circle of the 2 objects
if(shape1 == Entity::SHAPE_CIRCLE){
circleCentre = maths::Vector2(gbounds1.left + gbounds1.width / 2, gbounds1.top + gbounds1.height / 2);
circleCentre1 = circleCentre;
squareRect = getOriginalBoundingBox(object2);
rotation = object2.getRotation();
}else if(shape2 == Entity::SHAPE_CIRCLE){
circleCentre = maths::Vector2(gbounds2.left + gbounds2.width / 2, gbounds2.top + gbounds2.height / 2);
circleCentre2 = circleCentre;
squareRect = getOriginalBoundingBox(object1);
rotation = object1.getRotation();
}
maths::Vector2 squareCentre(squareRect.left + squareRect.width / 2, squareRect.top + squareRect.height / 2);
OBB* square = (shape1 == Entity::SHAPE_SQUARE ? &obb1 : &obb2);
maths::Vector2 relativeCircleCentre = circleCentre.rotate(-rotation, squareCentre); //get circle centre in relation to the rotated square
bool vertice = false;
maths::Vector2 axis;
maths::Vector2 topLeft(squareRect.left, squareRect.top);
maths::Vector2 topRight(squareRect.left + squareRect.width, squareRect.top);
maths::Vector2 botLeft(squareRect.left, squareRect.top + squareRect.height);
maths::Vector2 botRight(squareRect.left + squareRect.width, squareRect.top + squareRect.height);
//Get the closest vertex of the rectangle to the circle centre.
//The axis to check is the vector between these 2 points.
if(circleCentre.x < topLeft.x){
if(circleCentre.y < topLeft.y){
vertice = true;
axis = topLeft;
}else if(circleCentre.y > botLeft.y){
vertice = true;
axis = botLeft;
}else{
axis = maths::Vector2(topLeft - botLeft).normalise();
}
}else if(circleCentre.x > topRight.x){
if(circleCentre.y < topLeft.y){
vertice = true;
axis = topRight;
}else if(circleCentre.y > botLeft.y){
vertice = true;
axis = botRight;
}else{
axis = maths::Vector2(topRight - botRight).normalise();
}
}else{
if(circleCentre.y < topLeft.y){
axis = maths::Vector2(topRight - topLeft).normalise();
}else if(circleCentre.y > botLeft.y){
axis = maths::Vector2(botLeft - botRight).normalise();
}else{
//contains point!
}
}
if(vertice){
axis1.push_back(maths::Vector2(circleCentre - axis).normalise());
}else{
axis1.push_back(maths::Vector2(topRight - topLeft).normalise());
axis1.push_back(maths::Vector2(topRight - botRight).normalise());
}
}else{ //If both shapes are rectangles
//Get vectors for sides of shapes
maths::Vector2 Xside1(obb1.bot_left - obb1.bot_right);
maths::Vector2 Yside1(obb1.top_left - obb1.bot_left);
maths::Vector2 Xside2(obb2.bot_left - obb2.bot_right);
maths::Vector2 Yside2(obb2.top_left - obb2.bot_left);
//Axes requires are perpendicular to the sides of the shape
//Vector2.perpendicular() normalises for greater accuracy
axis1.push_back(Xside1.perpendicular());
axis1.push_back(Yside1.perpendicular());
axis2.push_back(Xside2.perpendicular());
axis2.push_back(Yside2.perpendicular());
}
//We have all the axes to check.
//Now find details on collisions with projections.
for(int i=0;i<axis1.size();i++){
//Get projection of axis for both shapes
maths::Vector2 axis = axis1[i];
Projection projection1 = project(obb1, axis);
if(shape1 == Entity::SHAPE_CIRCLE){
float radius = gbounds1.width / 2;
projection1 = projectCircle(circleCentre1, radius, axis);
}
Projection projection2 = project(obb2, axis);
if (shape2 == Entity::SHAPE_CIRCLE){
float radius = gbounds2.width / 2;
projection2 = projectCircle(circleCentre2, radius, axis);
}
//If a projection does not overlap, we know the objects do not collide so we can exit the function.
//Otherwise, the MTV (minimum translation vector required to make the objects not collide) is calculated.
if(!projection1.overlap(projection2)){
return MTV::NONE;
}else{
//The axis with the smallest overlap is the axis used to calculate MTV, so record it.
double o = projection1.getOverlap(projection2);
if(o < overlap){
overlap = o; //set smallest overlap
smallest = axis; //set smallest separation vector
}
}
}
//Repeat the same process as above with the other set of axes.
for(int i=0;i<axis2.size();i++){
maths::Vector2 axis = axis2[i];
Projection projection1 = project(obb1, axis);
if(shape1 == Entity::SHAPE_CIRCLE){
float radius = gbounds1.width/2;
projection1 = projectCircle(circleCentre1, radius, axis);
}
Projection projection2 = project(obb2,axis);
if(shape2 == Entity::SHAPE_CIRCLE){
float radius = gbounds2.width / 2;
projection2 = projectCircle(circleCentre2, radius, axis);
}
if(!projection1.overlap(projection2)){
return MTV::NONE;
}else{
double o = projection1.getOverlap(projection2);
if(o < overlap){
overlap = o;
smallest = axis;
}
}
}
//Get the vector from the centre of object 2 to the centre of object 1
maths::Vector2 centre1 = maths::Vector2(gbounds1.left + gbounds1.width / 2, gbounds1.top + gbounds1.height / 2);
maths::Vector2 centre2 = maths::Vector2(gbounds2.left + gbounds2.width / 2, gbounds2.top + gbounds2.height / 2);
maths::Vector2 between = centre1 - centre2;
//If the separation vector is in the opposite direction of 'between', flip it round by negating it
if(between.dot(smallest) < 0){
smallest = -smallest;
}
MTV mtv(overlap, smallest);
return mtv;
}
