问题
I'm using sprite kit as a part of a basic game. The game is that there is a guy who, depending on where you tap, moves to that location. Currently, the player is not affected by gravity (for the sake of playibility) but I'm trying to implement gravity. However, when I do turn gravity on for the player, I'm having trouble with my character falling through the ground. I've created a node for the ground and have disabled the ground physics (ground.physicsBody.dynamic = NO) but the character still flies right on through. I'm using the built in sprite-kit gravity feature, and if the physics is disabled, then theoretically the character should stop at the ground. I'm at a loss for why the problem still exists and would appreciate some help on this matter.
Code in the MyScene.m file:
//
// MyScene.m
// DodgeMan
//
// Created by Cormac Chester on 3/8/14.
// Copyright (c) 2014 Testman Industries. All rights reserved.
//
#import "MyScene.h"
#import "EndGameScene.h"
static const uint32_t redBallCategory = 0x1 << 0;
static const uint32_t playerCategory = 0x1 << 1;
@implementation MyScene
-(id)initWithSize:(CGSize)size
{
if (self = [super initWithSize:size])
{
//Sets up data storage
self.storeData = [NSUserDefaults standardUserDefaults];
//Sets gravity
self.physicsWorld.gravity = CGVectorMake(0,-2);
self.physicsWorld.contactDelegate = self;
//Set Background
self.backgroundColor = [SKColor colorWithRed:0.53 green:0.81 blue:0.92 alpha:1.0];
//Set Ground
SKSpriteNode *ground = [SKSpriteNode spriteNodeWithImageNamed:@"ground"];
ground.position = CGPointMake(CGRectGetMidX(self.frame), 34);
ground.xScale = 0.5;
ground.yScale = 0.5;
ground.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:ground.size];
ground.physicsBody.dynamic = NO;
ground.physicsBody.collisionBitMask = 1;
ground.physicsBody.usesPreciseCollisionDetection = YES;
//Player
self.posX = 50;
self.posY = 88;
self.playerSprite = [SKSpriteNode spriteNodeWithImageNamed:@"character"];
self.playerSprite.position = CGPointMake(self.posX, self.posY);
//Set Player Physics
self.playerSprite.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:self.playerSprite.size];
self.playerSprite.physicsBody.dynamic = NO;
self.playerSprite.physicsBody.categoryBitMask = playerCategory;
self.playerSprite.physicsBody.contactTestBitMask = redBallCategory;
self.playerSprite.physicsBody.collisionBitMask = 0;
self.playerSprite.physicsBody.usesPreciseCollisionDetection = YES;
//Score Label
self.scoreLabel = [SKLabelNode labelNodeWithFontNamed:@"Arial-BoldMT"];
self.scoreLabel.text = @"0";
self.scoreLabel.fontSize = 40;
self.scoreLabel.fontColor = [SKColor blackColor];
self.scoreLabel.position = CGPointMake(50, 260);
//Pause Button
self.pauseButton = [SKSpriteNode spriteNodeWithImageNamed:@"pauseButton"];
self.pauseButton.position = CGPointMake(self.frame.size.width / 2, self.frame.size.height - 40);
self.pauseButton.name = @"pauseButton";
//Pause Label
NSString *pauseMessage;
pauseMessage = @"Game Paused";
self.pauseLabel = [SKLabelNode labelNodeWithFontNamed:@"Arial-BoldMT"];
self.pauseLabel.text = pauseMessage;
self.pauseLabel.fontSize = 40;
self.pauseLabel.fontColor = [SKColor blackColor];
self.pauseLabel.position = CGPointMake(self.size.width/2, self.size.height/2);
//Set score
self.score = 0;
//Add nodes
[self addChild:ground];
[self addChild:self.playerSprite];
[self addChild:self.scoreLabel];
[self addChild:self.pauseButton];
}
return self;
}
//Add Red Ball
-(void)addBall
{
SKSpriteNode *redBall = [SKSpriteNode spriteNodeWithImageNamed:@"locationIndicator"];
int minY = redBall.size.height / 2;
int maxY = self.frame.size.height - redBall.size.height / 2;
int rangeY = maxY - minY;
int actualY = (arc4random() % rangeY) + minY;
//Initiates red ball offscreen
if (actualY >= 75)
{
//Prevents balls from spawning in the ground
redBall.position = CGPointMake(self.frame.size.width + redBall.size.width/2, actualY);
[self addChild:redBall];
}
redBall.physicsBody = [SKPhysicsBody bodyWithCircleOfRadius:redBall.size.width/2];
redBall.physicsBody.dynamic = YES;
redBall.physicsBody.categoryBitMask = redBallCategory;
redBall.physicsBody.contactTestBitMask = playerCategory;
redBall.physicsBody.collisionBitMask = 0;
redBall.physicsBody.affectedByGravity = NO;
redBall.physicsBody.usesPreciseCollisionDetection = YES;
//Determine speed of red ball
int minDuration = 3.0;
int maxDuration = 5.0;
int rangeDuration = maxDuration - minDuration;
int actualDuration = (arc4random() % rangeDuration) + minDuration;
// Create the actions
SKAction *actionMove = [SKAction moveTo:CGPointMake(-redBall.size.width/2, actualY) duration:actualDuration];
SKAction *actionMoveDone = [SKAction removeFromParent];
SKAction *ballCross = [SKAction runBlock:^{
self.score++;
self.scoreString = [NSString stringWithFormat:@"%i", self.score];
self.scoreLabel.text = self.scoreString;
NSLog(@"Score was incremented. Score is now %d", self.score);
}];
[redBall runAction:[SKAction sequence:@[actionMove, ballCross, actionMoveDone]]];
}
- (void)pauseScene
{
self.paused = YES;
[self addChild:self.pauseLabel];
}
- (void)updateWithTimeSinceLastUpdate:(CFTimeInterval)timeSinceLast
{
self.lastSpawnTimeInterval += timeSinceLast;
if (self.lastSpawnTimeInterval > 0.35) {
self.lastSpawnTimeInterval = 0;
[self addBall];
}
}
//Update Loop
-(void)update:(CFTimeInterval)currentTime
{
/* Called before each frame is rendered */
// Handle time delta.
CFTimeInterval timeSinceLast = currentTime - self.lastUpdateTimeInterval;
self.lastUpdateTimeInterval = currentTime;
if (timeSinceLast > 1) { //More than a second since last update
timeSinceLast = 1.0 / 120.0;
self.lastUpdateTimeInterval = currentTime;
}
[self updateWithTimeSinceLastUpdate:timeSinceLast];
}
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
/* Called when a touch begins */
[super touchesBegan:touches withEvent:event];
//Starts Timer
startTime = [NSDate date];
}
-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
/* Called when a touch ends */
[super touchesEnded:touches withEvent:event];
NSTimeInterval elapsedTime = [startTime timeIntervalSinceNow];
NSString *elapsedTimeString = [NSString stringWithFormat:@"Elapsed time: %f", elapsedTime];
NSLog(@"%@", elapsedTimeString);
for (UITouch *touch in touches)
{
//Gets location of touch
CGPoint location = [touch locationInNode:self];
NSLog(@"Touch Location X: %f \n Touch Location Y: %f", location.x, location.y);
SKNode *node = [self nodeAtPoint:location];
//Runs when pause button is pressed
if ([node.name isEqualToString:@"pauseButton"])
{
NSLog(@"Pause button pressed");
if (!self.paused)
{
[self pauseScene];
}
else if (self.paused)
{
self.paused = NO;
[self.pauseLabel removeFromParent];
}
}
else
{
//Prevents destination from being in the ground
if (location.y < 88)
{
location.y = 88;
}
//Moves and animates player
int velocity = 1000.0/1.0;
NSLog(@"Velocity: %i", velocity);
float realMoveDuration = self.size.width / velocity;
SKAction *actionMove = [SKAction moveTo:location duration:realMoveDuration];
[self.playerSprite runAction:[SKAction sequence:@[actionMove]]];
}
}
NSLog(@"Touch ended");
}
//Collision between ball and player - player dies
- (void)redBall:(SKSpriteNode *)redBall didCollideWithPlayer:(SKSpriteNode *)playerSprite
{
NSLog(@"Player died");
[redBall removeFromParent];
[playerSprite removeFromParent];
//Stores Final score
[self.storeData setObject:self.scoreString forKey:@"scoreStringKey"];
SKTransition *reveal = [SKTransition fadeWithDuration:0.5];
SKScene *endGameScene = [[EndGameScene alloc] initWithSize:self.size];
[self.view presentScene:endGameScene transition: reveal];
}
- (void)didBeginContact:(SKPhysicsContact *)contact
{
SKPhysicsBody *firstBody, *secondBody;
if (contact.bodyA.categoryBitMask < contact.bodyB.categoryBitMask)
{
firstBody = contact.bodyA;
secondBody = contact.bodyB;
}
else
{
firstBody = contact.bodyB;
secondBody = contact.bodyA;
}
//Red ball collides with the player
if ((firstBody.categoryBitMask & redBallCategory) != 0 && (secondBody.categoryBitMask & playerCategory) != 0)
{
[self redBall:(SKSpriteNode *) firstBody.node didCollideWithPlayer:(SKSpriteNode *) secondBody.node];
NSLog(@"Player and ball collided");
}
}
@end
回答1:
I would say your problem is due to this line
self.playerSprite.physicsBody.collisionBitMask = 0;
instead of that set it to the category with which collisions are to occur, for example
self.playerSprite.physicsBody.collisionBitMask = redBallCategory;
回答2:
you need to define the boundaries of the view related to the character. something like the following where the views bounds are declared then the character is defined and confined to the borders. the following is that sample code:
- (void)confineToBounds {
CGPoint correctedMonkeyPos = _monkey.position;
CGPoint lowerLeft = CGPointZero;
CGPoint upperRight = CGPointMake(self.size.width, self.size.height);
if(correctedMonkeyPos.x <= lowerLeft.x) {correctedMonkeyPos.x = lowerLeft.x;}
if(correctedMonkeyPos.x >= upperRight.x) {correctedMonkeyPos.x = upperRight.x;}
if(correctedMonkeyPos.y <= lowerLeft.y) {correctedMonkeyPos.y = lowerLeft.y;}
if(correctedMonkeyPos.y >= upperRight.y) {correctedMonkeyPos.y = upperRight.y;}
_monkey.position = correctedMonkeyPos;
}
来源：https://stackoverflow.com/questions/22315103/character-falling-through-ground