Messages

1

Graphics / Re: Conversion from Box2D to SFML creates gap

« on: April 23, 2016, 04:33:47 pm »

Thank you to everyone who helped out! I finally figured out what the problem was and updated the post. Thanks again, you guys are awesome!

2

Graphics / Re: Conversion from Box2D to SFML creates gap

« on: April 23, 2016, 06:17:23 am »

Thanks for your example! Where are you adding the position? I'm beginning to wonder if maybe the origin is off... I mean, the shape is being drawn at the correct size, and acts correctly, it's just not in the right spot.

3

Graphics / Re: Conversion from Box2D to SFML creates gap

« on: April 23, 2016, 01:24:24 am »

Thanks for the continuing responses! I think the rotation is correct because the shape acts the way I would expect it to. It seems as though there is just a gap between the body in box2d and the texture. The strange part is that the gap seems to scale with non reflected points. If I define a triangle with one side down, the bottom will be drawn inside the ground, and other bodies will be pushed away from the top tip at the same distance. The closer I get to a rectangle, the less of a gap, to the point that if I define a perfect rectangle, there's no gap.

4

Graphics / Re: Conversion from Box2D to SFML creates gap

« on: April 22, 2016, 11:10:42 pm »

The good direction? I'm turning it according to the angle in box2d. Here's the code for how I'm entering polygons (sorry, I know this is box2d, but I'm not sure if the problem is with it or how I'm translating to SFML).

b2Body* PhysicsArea::addComponentWithName(std::string name,b2Vec2 origin, b2Vec2 points[], int pointCount, float rotation) {

    PhysicsAreaComponent *comp = components.at(name);
    b2BodyDef def;
    def.position = b2Vec2(origin.x/SCALE,-origin.y/SCALE);
        def.type = comp->bodyType;

        b2Body *body = world.CreateBody(&def);

    for (int i = 0; i < pointCount; i++) points[i].Set(points[i].x/SCALE,-points[i].y/SCALE);


        b2PolygonShape shape;
        shape.Set(points, pointCount);

        b2FixtureDef fixture;
        fixture.density = comp->density;
        fixture.friction = comp->friction;
        fixture.shape = &shape;
        body->CreateFixture(&fixture);
        body->SetUserData(&comp->name);
        std::string *compID = (static_cast<std::string*>(body->GetUserData()));
    return body;

}
 

5

Graphics / Re: Conversion from Box2D to SFML creates gap

« on: April 22, 2016, 10:43:47 pm »

Thanks for the reply! I flipped the sign on the y coordinates when I create, and when I draw, but the problem persists. Here's a screenshot of several polygons at rest.

6

Graphics / Conversion from Box2D to SFML creates gap

« on: April 22, 2016, 09:01:18 pm »

I have the following bit of code, which basically takes a Box2D world and converts it to SFML shapes that are then drawn to the screen. For rectangles, this works perfectly, but for other polygons, it produces a strange gap between the object and it's representation in Box2D which manifests as a gap between objects on screen. Can anyone see why this might be the case?

b2PolygonShape* polyShape = (b2PolygonShape*) bodyFixture->GetShape();

ConvexShape shapeToFill;
shapeToFill.setPosition(body->GetWorldCenter().x*SCALE, body->GetWorldCenter().y*SCALE);

int vertCount = polyShape->GetVertexCount();
shapeToFill.setPointCount(vertCount);

for(int vert = 0 ; vert < vertCount ; vert++) {
   b2Vec2 aVertex = polyShape->GetVertex(vert);
   sf::Vector2f sfVect;
   sfVect.x = aVertex.x*SCALE;
   sfVect.y = aVertex.y*SCALE;
   shapeToFill.setPoint(vert,sfVect);
}
shapeToFill.setRotation(180/b2_pi * body->GetAngle());
 

UPDATE, SOLVED: The problem lay with this line:

shapeToFill.setPosition(body->GetWorldCenter().x*SCALE, body->GetWorldCenter().y*SCALE);

which needed to be changed to:

shapeToFill.setPosition(body->GetPosition().x*SCALE, -body->GetPosition().y*SCALE);

The world center of a body is not it's centroid, but it's local origin.

7

Window / sf::Mouse::getPosition slightly off

« on: April 20, 2016, 07:56:18 pm »

I'm using:
   sf::Vector2i pixelPos = sf::Mouse::getPosition(*this);
   sf::Vector2f worldPos = this->mapPixelToCoords(pixelPos);
to get the position of mouse clicks within a world. When I draw draw things based on these coordinates, everything is drawing slightly higher than where the mouse actually was. This is consistent no matter how I change the view, it's always off by the same amount. If I resize the window, it's off in both axis' by more, consistently. I know this is somewhat vague, as the code for the window is spread out across three or four classes. I'm just wondering if there is a sample program out there that deals with window resizes so I can see what's going on. Thanks!