如何在Box2d中制作歪斜图像（b2body）？

Question

I am new in Box2d and learning myself. I am learning Box2d from here

I want to make a body and want to give b2body a angle so that it will look like body is stand like skew line, like slope.

This is my code.

for(int i = 0; i < 4; i++) {

    static int padding=20;

    // Create block and add it to the layer
    CCSprite *block = [CCSprite spriteWithFile:@"slope.png"];
    int xOffset = padding+block.contentSize.width/2+ ((block.contentSize.width+padding)*i);
    block.position = ccp(xOffset, 250);
    block.tag = 2;
    [self addChild:block];

    // Create block body
    b2BodyDef blockBodyDef;
    blockBodyDef.type = b2_staticBody;   //b2_dynamicBody
    blockBodyDef.position.Set(xOffset/PTM_RATIO, 250/PTM_RATIO);
    blockBodyDef.userData = block;
    b2Body *blockBody = _world->CreateBody(&blockBodyDef);

    // Create block shape
    b2PolygonShape blockShape;
    blockShape.SetAsBox(block.contentSize.width/PTM_RATIO/2,
                        block.contentSize.height/PTM_RATIO/2);

    // Create shape definition and add to body
    b2FixtureDef blockShapeDef;
    blockShapeDef.shape = &blockShape;
    blockShapeDef.density = 10.0;
    blockShapeDef.friction = 0.0;
    blockShapeDef.restitution = 0.1f;
    blockBody->CreateFixture(&blockShapeDef);            
}

In this code I made 4 b2body horizontically. Now I want these in vertical and slightly skew, like a slope.

I am not able to do this yet.

I dont know I have to give angel to the body or something else. Not able to find sample code and good tutorials of Box2d.

Is there any site available where I can find some xcode Box2d demo for beginners? Or some code like applications we have UIButtons, UILabel, UITextfiled programatically, can I find Box2d codes like this?

In this demo I am trying to make 4 static slope image and from the left upper side corner I have to push ball(b2dynamicbody). The ball will go through these 4 static body and the ball will turn according to the slope.

Any Idea or suggestions would be highly welcome.

Answer 1

Replace this code in your sample and get a sloppy body

// Create block body
b2BodyDef blockBodyDef;
blockBodyDef.type = b2_staticBody;   //b2_dynamicBody
blockBodyDef.position.Set(200/PTM_RATIO, 250/PTM_RATIO);
blockBodyDef.userData = block;
b2Body *blockBody = _world->CreateBody(&blockBodyDef);

// Create block shape
b2PolygonShape blockShape;

int num = 3;
b2Vec2 verts[] = {
    b2Vec2(-27.5f / PTM_RATIO, -296.6f / PTM_RATIO),
    b2Vec2(-14.3f / PTM_RATIO, -127.2f / PTM_RATIO),
    b2Vec2(-281.0f / PTM_RATIO, -288.4f / PTM_RATIO)
};
blockShape.Set(verts, num);

// Create shape definition and add to body
b2FixtureDef blockShapeDef;
blockShapeDef.shape = &blockShape;
blockShapeDef.density = 10.0;
blockShapeDef.friction = 0.0;
blockShapeDef.restitution = 0.1f;
blockBody->CreateFixture(&blockShapeDef);

Good luck, feel free to ask your queries.