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dungeon-gunner/source/World.cpp

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/*
* World.cpp
*
* Created on: 29.08.2012
* Author: Felix
*/
#include "World.h"
#include <algorithm>
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#include <assert.h>
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#include <Thor/Vectors.hpp>
#include "util/Log.h"
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/**
* Insert a drawable into the group. Drawables should only be handled with shared_ptr.
* An object can't be inserted more than once at the same level.
*/
void
World::insert(std::shared_ptr<Sprite> drawable) {
#ifndef NDEBUG
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Sprite::Category cat = drawable->getCategory();
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auto item = std::find(mDrawables[cat].begin(), mDrawables[cat].end(), drawable);
assert(item == mDrawables[cat].end());
#endif
mDrawables[drawable->getCategory()].push_back(drawable);
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}
/**
* Removes a drawable from the group.
*/
void
World::remove(std::shared_ptr<Sprite> drawable) {
for (auto v = mDrawables.begin(); v != mDrawables.end(); v++) {
auto item = std::find(v->second.begin(), v->second.end(), drawable);
if (item != v->second.end()) {
v->second.erase(item);
}
}
}
/**
* Checks for collisions and applies movement, also removes sprites if
* Sprite::getDelete returns true.
*
* This method can be improved by only testing each pair of sprites once,
* and using the result for both. Applying movement should be done in
* testCollision, always applying the part that causes no collision.
*/
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void
World::step(int elapsed) {
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for (auto v = mDrawables.begin(); v != mDrawables.end(); v++) {
for (auto it = v->second.begin(); it != v->second.end(); ) {
auto spriteA = *it;
if (spriteA->getDelete()) {
remove(spriteA);
}
else {
sf::Vector2f speed = spriteA->getSpeed();
speed *= elapsed / 1000.0f;
bool overlap = false;
for (auto w = mDrawables.begin(); w != mDrawables.end(); w++) {
for (auto spriteB : w->second) {
if (spriteA == spriteB) {
continue;
}
// Ignore anything that is filtered by masks.
if (!spriteA->collisionEnabled(spriteB->getCategory()) ||
!spriteB->collisionEnabled(spriteA->getCategory())) {
continue;
}
if (testCollision(spriteA, spriteB, elapsed)) {
spriteA->onCollide(spriteB);
overlap = true;
}
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}
}
if (!overlap) {
spriteA->setPosition(spriteA->getPosition() + speed);
}
it++;
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}
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}
}
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}
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/**
* Tests for collisions using Seperating Axis Theorem (SAT).
*
* http://www.metanetsoftware.com/technique/tutorialA.html
*
* @param spriteA, spriteB Pair of sprites which to test for collision/overlapping.
* @param elapsed Time elapsed in this step.
* @return True if both sprites will be overlapping after their current movement.
*/
bool
World::testCollision(std::shared_ptr<Sprite> spriteA,
std::shared_ptr<Sprite> spriteB, int elapsed) const {
// circle-circle collision
if ((spriteA->mShape.type == Sprite::Shape::Type::CIRCLE) &&
(spriteB->mShape.type == Sprite::Shape::Type::CIRCLE)) {
sf::Vector2f axis = spriteA->getPosition() - spriteB->getPosition();
// If both objects are at the exact same position, allow any movement for unstucking.
if (axis == sf::Vector2f()) {
return true;
}
axis = thor::unitVector(axis);
float centerA = thor::dotProduct(axis, spriteA->getPosition());
float radiusA = std::static_pointer_cast<sf::CircleShape>(
spriteA->mShape.shape)->getRadius();
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float movementA = thor::dotProduct(axis, spriteA->getSpeed() * (elapsed / 1000.0f));
float centerB = thor::dotProduct(axis, spriteB->getPosition());
float radiusB = std::static_pointer_cast<sf::CircleShape>(
spriteB->mShape.shape)->getRadius();
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float movementB = thor::dotProduct(axis, spriteB->getSpeed() * (elapsed / 1000.0f));
// Allow movement if sprites are moving apart.
return Interval(centerA, radiusA).getOverlap(Interval(centerB, radiusB)).getLength() <
Interval(centerA + movementA, radiusA).getOverlap(
Interval(centerB + movementB, radiusB)).getLength();
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}
// circle-rect collision
if (((spriteA->mShape.type == Sprite::Shape::Type::CIRCLE) &&
(spriteB->mShape.type == Sprite::Shape::Type::RECTANGLE)) ||
((spriteA->mShape.type == Sprite::Shape::Type::RECTANGLE) &&
(spriteB->mShape.type == Sprite::Shape::Type::CIRCLE))) {
std::shared_ptr<Sprite> circle = spriteA;
std::shared_ptr<Sprite> rect = spriteB;
if (circle->mShape.type != Sprite::Shape::Type::CIRCLE) {
std::swap(circle, rect);
}
float radius =
std::static_pointer_cast<sf::CircleShape>(circle->mShape.shape)->getRadius();
sf::Vector2f halfsize = rect->getSize() / 2.0f;
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sf::Vector2f circlePos = circle->getPosition();
sf::Vector2f rectPos = rect->getPosition();
// Only circle movement as rectangles don't move.
sf::Vector2f circleMovement = circle->getSpeed() * (elapsed / 1000.0f);
// We assume that rectangles are always axis aligned.
float overlapNoMovementX = Interval(circlePos.x, radius)
.getOverlap(Interval (rectPos.x, halfsize.x)).getLength();
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float overlapMovementX = Interval(circlePos.x + circleMovement.x, radius)
.getOverlap(Interval (rectPos.x, halfsize.x)).getLength();
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float overlapNoMovementY = Interval(circlePos.y, radius)
.getOverlap(Interval (rectPos.y, halfsize.y)).getLength();
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float overlapMovementY = Interval(circlePos.y + circleMovement.y, radius)
.getOverlap(Interval (rectPos.y, halfsize.y)).getLength();
bool xyCollisionResult = (((overlapNoMovementX < overlapMovementX) &&
(overlapNoMovementY > 0)) ||
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((overlapNoMovementY < overlapMovementY) && (overlapNoMovementX > 0)));
// If circle center is overlapping rectangle on x or y axis, we can take xyCollisionResult.
if (Interval(rectPos.x, halfsize.x).isInside(circlePos.x) ||
Interval(rectPos.y, halfsize.y).isInside(circlePos.y)) {
return xyCollisionResult;
}
// Test if the circle is colliding with a corner of the rectangle.
else if (xyCollisionResult) {
// This is the same as circle-circle collision.
sf::Vector2f axis = circle->getPosition() - rect->getPosition();
// If both objects are at the exact same position, allow any
// movement for unstucking.
if (axis == sf::Vector2f()) {
return true;
}
axis = thor::unitVector(axis);
float circlePosProjected = thor::dotProduct(axis, circlePos);
float movementProjected = thor::dotProduct(axis, circleMovement);
float rectPosProjected = thor::dotProduct(axis, rectPos);
// For corner projections, those on the same line with the rect
// center are equal by value, so we only need one on each axis
// and take the maximum.
float rectHalfWidthProjected = std::max(
abs(thor::dotProduct(axis, halfsize)),
abs(thor::dotProduct(axis,
sf::Vector2f(halfsize.x, -halfsize.y))));
// Allow movement if sprites are moving apart.
return Interval(circlePosProjected, radius)
.getOverlap(Interval(rectPosProjected, rectHalfWidthProjected))
.getLength() <
Interval(circlePosProjected + movementProjected, radius)
.getOverlap(Interval(rectPosProjected, rectHalfWidthProjected))
.getLength();
}
// If there is no collision on x and y axis, there can't be one at all.
else {
return false;
}
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}
// Rectangles can't move and thus not collide.
return false;
}
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/**
* Draws all elements in the group.
*/
void
World::draw(sf::RenderTarget& target, sf::RenderStates states) const {
for (auto v = mDrawables.begin(); v != mDrawables.end(); v++) {
for (auto item : v->second) {
target.draw(static_cast<sf::Drawable&>(*item), states);
}
}
}
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/**
* Creates an interval from a center point and a radius. The interval
* ranges from center - radius to center + radius.
*/
World::Interval::Interval(float center, float radius) :
start(center - radius),
end(center + radius) {
}
/**
* Returns the overlap between two intervals, e.g. the overlap between
* intervals (1,3) and (2,4) is (2,3).
*/
World::Interval
World::Interval::getOverlap(Interval other) const {
if ((start == other.start) && (end == other.end)) {
return *this;
}
Interval smaller = *this;
Interval bigger = other;
if (smaller.start > bigger.start) {
std::swap(smaller, bigger);
}
Interval iv(0, 0);
if (bigger.start < smaller.end) {
iv.start = bigger.start;
iv.end = smaller.end;
}
else {
iv.start = iv.end = 0.0f;
}
return iv;
}
/**
* Returns true if the point is inside the interval.
*/
bool
World::Interval::isInside(float point) const {
return start < point && point < end;
}
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/**
* Returns the length of the interval (distance between start and end).
*/
float
World::Interval::getLength() {
return end - start;
}