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« on: February 27, 2011, 05:27:07 pm »
Try this:
/*
* File: collision.cpp
* Author: Nick
*
* Created on 30 January 2009, 11:02
*/
#include <SFML/Graphics.hpp>
#include "collision.h"
Collision::Collision() {
}
Collision::~Collision() {
}
sf::IntRect Collision::GetAABB(const sf::Sprite& Object) {
//Get the top left corner of the sprite regardless of the sprite's center
//This is in Global Coordinates so we can put the rectangle back into the right place
sf::Vector2f pos = Object.TransformToGlobal(sf::Vector2f(0, 0));
//Store the size so we can calculate the other corners
sf::Vector2f size = Object.GetSize();
float Angle = Object.GetRotation();
//Bail out early if the sprite isn't rotated
if (Angle == 0.0f) {
return sf::IntRect(static_cast<int> (pos.x),
static_cast<int> (pos.y),
static_cast<int> (pos.x + size.x),
static_cast<int> (pos.y + size.y));
}
//Calculate the other points as vectors from (0,0)
//Imagine sf::Vector2f A(0,0); but its not necessary
//as rotation is around this point.
sf::Vector2f B(size.x, 0);
sf::Vector2f C(size.x, size.y);
sf::Vector2f D(0, size.y);
//Rotate the points to match the sprite rotation
B = RotatePoint(B, Angle);
C = RotatePoint(C, Angle);
D = RotatePoint(D, Angle);
//Round off to int and set the four corners of our Rect
int Left = static_cast<int> (MinValue(0.0f, B.x, C.x, D.x));
int Top = static_cast<int> (MinValue(0.0f, B.y, C.y, D.y));
int Right = static_cast<int> (MaxValue(0.0f, B.x, C.x, D.x));
int Bottom = static_cast<int> (MaxValue(0.0f, B.y, C.y, D.y));
Left += pos.x;
Top += pos.y;
//Create a Rect from out points and move it back to the correct position on the screen
sf::IntRect AABB = sf::IntRect(Left, Top, size.x, size.y);
//AABB.Offset(static_cast<int> (pos.x), static_cast<int> (pos.y));
return AABB;
}
float Collision::MinValue(float a, float b, float c, float d) {
float min = a;
min = (b < min ? b : min);
min = (c < min ? c : min);
min = (d < min ? d : min);
return min;
}
float Collision::MaxValue(float a, float b, float c, float d) {
float max = a;
max = (b > max ? b : max);
max = (c > max ? c : max);
max = (d > max ? d : max);
return max;
}
sf::Vector2f Collision::RotatePoint(const sf::Vector2f& Point, float Angle) {
Angle = Angle * RADIANS_PER_DEGREE;
sf::Vector2f RotatedPoint;
RotatedPoint.x = Point.x * cos(Angle) + Point.y * sin(Angle);
RotatedPoint.y = -Point.x * sin(Angle) + Point.y * cos(Angle);
return RotatedPoint;
}
bool Collision::PixelPerfectTest(const sf::Sprite& Object1, const sf::Sprite& Object2, sf::Uint8 AlphaLimit) {
//Get AABBs of the two sprites
sf::IntRect Object1AABB = GetAABB(Object1);
sf::IntRect Object2AABB = GetAABB(Object2);
sf::IntRect Intersection;
if (Object1AABB.Intersects(Object2AABB, Intersection)) {
//We've got an intersection we need to process the pixels
//In that Rect.
//Bail out now if AlphaLimit = 0
if (AlphaLimit == 0) return true;
//There are a few hacks here, sometimes the TransformToLocal returns negative points
//Or Points outside the image. We need to check for these as they print to the error console
//which is slow, and then return black which registers as a hit.
sf::IntRect O1SubRect = Object1.GetSubRect();
sf::IntRect O2SubRect = Object2.GetSubRect();
sf::Vector2i O1SubRectSize(O1SubRect.Width, O1SubRect.Height);
sf::Vector2i O2SubRectSize(O2SubRect.Width, O2SubRect.Height);
sf::Vector2f o1v;
sf::Vector2f o2v;
//Loop through our pixels
for (int i = Intersection.Left; i < (Intersection.Left+Intersection.Width); i++) {
for (int j = Intersection.Top; j < (Intersection.Top+Intersection.Height); j++) {
o1v = Object1.TransformToLocal(sf::Vector2f(i, j)); //Creating Objects each loop :(
o2v = Object2.TransformToLocal(sf::Vector2f(i, j));
//Hack to make sure pixels fall withint the Sprite's Image
if (o1v.x > 0 && o1v.y > 0 && o2v.x > 0 && o2v.y > 0 &&
o1v.x < O1SubRectSize.x && o1v.y < O1SubRectSize.y &&
o2v.x < O2SubRectSize.x && o2v.y < O2SubRectSize.y) {
//If both sprites have opaque pixels at the same point we've got a hit
if ((Object1.GetPixel(static_cast<int> (o1v.x), static_cast<int> (o1v.y)).a > AlphaLimit) &&
(Object2.GetPixel(static_cast<int> (o2v.x), static_cast<int> (o2v.y)).a > AlphaLimit)) {
return true;
}
}
}
}
return false;
}
return false;
}
bool Collision::CircleTest(const sf::Sprite& Object1, const sf::Sprite& Object2) {
//Simplest circle test possible
//Distance between points <= sum of radius
float Radius1 = (Object1.GetSize().x + Object1.GetSize().y) / 4;
float Radius2 = (Object2.GetSize().x + Object2.GetSize().y) / 4;
float xd = Object1.GetPosition().x - Object2.GetPosition().x;
float yd = Object1.GetPosition().y - Object2.GetPosition().y;
return sqrt(xd * xd + yd * yd) <= Radius1 + Radius2;
}
//From Rotated Rectangles Collision Detection, Oren Becker, 2001
bool Collision::BoundingBoxTest(const sf::Sprite& Object1, const sf::Sprite& Object2) {
sf::Vector2f A, B, C, BL, TR;
sf::Vector2f HalfSize1 = Object1.GetSize();
sf::Vector2f HalfSize2 = Object2.GetSize();
//For somereason the Vector2d divide by operator
//was misbehaving
//Doing it manually
HalfSize1.x /= 2;
HalfSize1.y /= 2;
HalfSize2.x /= 2;
HalfSize2.y /= 2;
//Get the Angle we're working on
float Angle = Object1.GetRotation() - Object2.GetRotation();
float CosA = cos(Angle * RADIANS_PER_DEGREE);
float SinA = sin(Angle * RADIANS_PER_DEGREE);
float t, x, a, dx, ext1, ext2;
//Normalise the Center of Object2 so its axis aligned an represented in
//relation to Object 1
C = Object2.GetPosition();
C -= Object1.GetPosition();
C = RotatePoint(C, Object2.GetRotation());
//Get the Corners
BL = TR = C;
BL -= HalfSize2;
TR += HalfSize2;
//Calculate the vertices of the rotate Rect
A.x = -HalfSize1.y*SinA;
B.x = A.x;
t = HalfSize1.x*CosA;
A.x += t;
B.x -= t;
A.y = HalfSize1.y*CosA;
B.y = A.y;
t = HalfSize1.x*SinA;
A.y += t;
B.y -= t;
t = SinA * CosA;
// verify that A is vertical min/max, B is horizontal min/max
if (t < 0) {
t = A.x;
A.x = B.x;
B.x = t;
t = A.y;
A.y = B.y;
B.y = t;
}
// verify that B is horizontal minimum (leftest-vertex)
if (SinA < 0) {
B.x = -B.x;
B.y = -B.y;
}
// if rr2(ma) isn't in the horizontal range of
// colliding with rr1(r), collision is impossible
if (B.x > TR.x || B.x > -BL.x) return false;
// if rr1(r) is axis-aligned, vertical min/max are easy to get
if (t == 0) {
ext1 = A.y;
ext2 = -ext1;
}// else, find vertical min/max in the range [BL.x, TR.x]
else {
x = BL.x - A.x;
a = TR.x - A.x;
ext1 = A.y;
// if the first vertical min/max isn't in (BL.x, TR.x), then
// find the vertical min/max on BL.x or on TR.x
if (a * x > 0) {
dx = A.x;
if (x < 0) {
dx -= B.x;
ext1 -= B.y;
x = a;
} else {
dx += B.x;
ext1 += B.y;
}
ext1 *= x;
ext1 /= dx;
ext1 += A.y;
}
x = BL.x + A.x;
a = TR.x + A.x;
ext2 = -A.y;
// if the second vertical min/max isn't in (BL.x, TR.x), then
// find the local vertical min/max on BL.x or on TR.x
if (a * x > 0) {
dx = -A.x;
if (x < 0) {
dx -= B.x;
ext2 -= B.y;
x = a;
} else {
dx += B.x;
ext2 += B.y;
}
ext2 *= x;
ext2 /= dx;
ext2 -= A.y;
}
}
// check whether rr2(ma) is in the vertical range of colliding with rr1(r)
// (for the horizontal range of rr2)
return !((ext1 < BL.y && ext2 < BL.y) ||
(ext1 > TR.y && ext2 > TR.y));
}
The problem is that the latter two arguments rect takes was changed in sfml2 (takes left,top,width,height now), as a result GetAABB needs a tweak. Top and Left also need manually offsetting to return the co-ords to global as well, as Offset() no longer exists.
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