Messages

1

General / Re: Rotated Rectangle Collision Implementation

« on: September 07, 2013, 10:09:22 pm »

I had believed that the problem was with the values that I had been inputting, as after I rotated the rectangles, I did not reassign them as top-left, top-right, etc.  However, apparently that was not the case, as it still doesn't work, and registers a collision with basically any values.

For example, A (219, 128) (232, 119) (241, 132) (228, 141) and B (246, 246) (254, 246) (246, 254) (254, 254) registers a collision.

So I once again have no idea what's wrong with the code.

2

General / Re: Rotated Rectangle Collision Implementation

« on: September 03, 2013, 01:32:33 am »

For example, when Rect A is equal to [(242, 133), (228, 142), (233, 120), (219, 129)] and Rect B is equal to [(246, 246), (254, 246), (246, 254), (254, 254)] it registers a collision.  It computes the axes to be (-13, 9), (9, 13), (0, -8), (-8, 0), which I believe is correct.

3

General / Rotated Rectangle Collision Implementation

« on: September 03, 2013, 12:47:48 am »

Recently I've had to implement collision detection between rotated rectangle.  Following this algorithm, http://www.gamedev.net/page/resources/_/technical/game-programming/2d-rotated-rectangle-collision-r2604, I created a function to take the four corners of two rectangles and return a bool as to whether or not they collide.  However, for some reason it registers collisions even when no collisions occur.

bool Game_State::RotatedRectCollision(sf::Vector2f UL1, sf::Vector2f UR1, sf::Vector2f LL1, sf::Vector2f LR1, sf::Vector2f UL2, sf::Vector2f UR2, sf::Vector2f LL2, sf::Vector2f LR2)
{
        sf::Vector2f RectA[4];
        sf::Vector2f RectB[4];
       
        RectA[0] = UL1;
        RectA[1] = UR1;
        RectA[2] = LL1;
        RectA[3] = LR1;
       
        RectB[0] = UL2;
        RectB[1] = UR2;
        RectB[2] = LL2;
        RectB[3] = LR2;
       
        sf::Vector2f Axes[4];
        Axes[0] = sf::Vector2f(UR1.x - UL1.x, UR1.y - UL1.y);
        Axes[1] = sf::Vector2f(UR1.x - LR1.x, UR1.y - LR1.y);
        Axes[2] = sf::Vector2f(UL2.x - LL2.x, UL2.y - LL2.y);
        Axes[3] = sf::Vector2f(UL2.x - UR2.x, UL2.y - UR2.y);

        float ScalarVal[8];

        for(int i = 0; i < 4; i++)
        {
                sf::Vector2f Proj[8];
                int curProj = 0;

                for(int j = 0; j < 4; j++)
                {
                        Proj[curProj].x = Axes[i].x * (RectA[j].x * Axes[i].x + RectA[j].y * Axes[i].y)/(Axes[i].x * Axes[i].x + Axes[i].y * Axes[i].y);
                        Proj[curProj].y = Axes[i].y * Proj[curProj].x / Axes[i].x;

                        curProj++;

                        Proj[curProj].x = Axes[i].x * (RectB[j].x * Axes[i].x + RectB[j].y * Axes[i].y)/(Axes[i].x * Axes[i].x + Axes[i].y * Axes[i].y);
                        Proj[curProj].y = Axes[i].y * Proj[curProj].x / Axes[i].x;

                        curProj++;
       
                }

                for(int j = 0; j < 8; j++)
                {
                        ScalarVal[j] = Proj[j].x * Axes[i].x + Proj[j].y * Axes[i].y;
                }
               
                float min_a = ScalarVal[0];
                float min_b = ScalarVal[4];
                float max_a = ScalarVal[0];
                float max_b = ScalarVal[4];

                for(int j = 1; j < 4; j++)
                {
                        min_a = std::min(min_a, ScalarVal[j]);
                        min_b = std::min(min_b, ScalarVal[j + 4]);
                        max_a = std::max(max_a, ScalarVal[j]);
                        max_b = std::max(max_b, ScalarVal[j + 4]);

                }

                if((min_b > min_a) && (max_b < min_a))
                {
                        return false;
                }
        }

        return true;

}

4

General / Re: Rotating Help

« on: September 01, 2013, 01:58:13 am »

Ah, I was accidentally applying the Transform before rotating it.  However, I changed it and it still has the same problem.  Even if I change the rotation to some other value, such as 45, it still does not rotate.

float offset_x = collide_rect.width / 2 + collide_rect.left;
float offset_y = collide_rect.height / 2 + collide_rect.top;
       
sf::Transform t;
t.rotate(sprite.getRotation(), offset_x, offset_y);
       
for(int i = 0; i < 4; i++)
{
        t.transformPoint(collide_box[i]);
                       
}

5

General / Re: Rotating Help

« on: September 01, 2013, 01:12:56 am »

float rad = sprite.getRotation() / 180 * PI;

this looks wrong.
Unless your trying to turn from rad to deg, but sprite.getRoation() doesn't return radians.

Isn't the equation for transforming degrees to radians * PI/180?

However I still suggest to use sf::Transform (nice interface to a 3D matrix) or even create a class and derive from sf::Transformable, so you can apply the rotation in an easy way and reuse the transformation for all the different points. Just look it up in the documentation/tutorial, it's really simple to use.

I'm trying to use sf::Transform, but I don't think I quite understand how it works.

        collide_box[0] = sf::Vector2f(collide_rect.left, collide_rect.top);
collide_box[1] = sf::Vector2f(collide_rect.left + collide_rect.width, collide_rect.top);
collide_box[3] = sf::Vector2f(collide_rect.left, collide_rect.top + collide_rect.height);
collide_box[2] = sf::Vector2f(collide_rect.left + collide_rect.width, collide_rect.top + collide_rect.height);

float offset_x = collide_rect.width / 2 + collide_rect.left;
float offset_y = collide_rect.height / 2 + collide_rect.top;
float rad = sprite.getRotation() * PI / 180;
       
for(int i = 0; i < 4; i++)
{
        sf::Transform t;
        t.transformPoint(collide_box[i]);
        t.rotate(rad, offset_x, offset_y);
}

This is just giving me a point outside of the rectangle.

6

General / Re: Rotating Help

« on: August 31, 2013, 10:34:43 pm »

I am using this rotated array in order to check for collisions between sprites.  I don't know how else I would be able to get the rotated rectangle's coordinates.

As for why it doesn't work, when I draw lines between the points, they stretch to parallelograms.   

7

General / Rotating Help

« on: August 31, 2013, 10:04:28 pm »

I have been trying to rotate an array of four points that represent a rectangle to match a rotated rectangle sprite.  This is the function I've been using, but it doesn't seem to be working. 

collide_box[0] = sf::Vector2f(collide_rect.left, collide_rect.top);
collide_box[1] = sf::Vector2f(collide_rect.left + collide_rect.width, collide_rect.top);
collide_box[2] = sf::Vector2f(collide_rect.left, collide_rect.top + collide_rect.height);
collide_box[3] = sf::Vector2f(collide_rect.left + collide_rect.width, collide_rect.top + collide_rect.height);
       
float offset_x = collide_rect.width / 2 + collide_rect.left;
float offset_y = collide_rect.height / 2 + collide_rect.top;

float rad = sprite.getRotation() / 180 * PI;

for(int i = 0; i < 4; i++)
{
        collide_box[i].x -= offset_x;
        collide_box[i].y -= offset_y;

        collide_box[i].x = collide_box[i].x * std::cos(rad) - collide_box[i].y * std::sin(rad);
        collide_box[i].y = collide_box[i].x * std::sin(rad) + collide_box[i].y * std::cos(rad);
               
        collide_box[i].x += offset_x;
        collide_box[i].y += offset_y;

}
 

Thank you.

8

General / Release Build Has No Graphics

« on: May 23, 2013, 10:49:22 pm »

Let me first say that I'm not sure if my problem is with SFML or Visual C++ 2010.  I'm hoping somebody can help me either way  .  I have an SFML program that works fine in Debug, and even after building Release and running it from Visual C++ it runs fine.  However, when I run the Release .exe in its location, without the IDE, the graphics do not show up at all.    I have changed the SFML .libs to static, and have added the only image file to the Resource files (I'm not sure if this is needed).  Any solutions?

9

Graphics / Re: Problem with Returning Sprite

« on: May 23, 2013, 08:59:35 pm »

Thank you so much, I really feel like an idiot now.

10

Graphics / Problem with Returning Sprite

« on: May 23, 2013, 08:27:36 pm »

I just recently got back into coding c++ after about a year's hiatus, so this may well be a basic mistake.  I decided to drop SDL and I am starting to learn SFML.  I created a basic Pong game, but when I tried to implement classes it didn't work.  I tried to simplify the problem by just getting a class to represent an image, however I keep raising an error.  I've torn my hair out trying to fix this, but I think I've reached a point where even if the solution was at first obvious, I will not find it.  The program only encompasses 3 files.

main.cpp

#include <SFML/Graphics.hpp>
#include <SFML/Window.hpp>
#include <windows.h>
#include "ball.h"



int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
               LPSTR lpCmdLine, int nCmdShow)
{
    sf::RenderWindow window(sf::VideoMode(200, 300), "Test");
   Ball ball;
       
    while (window.isOpen())
    {
        sf::Event event;
        while (window.pollEvent(event))
        {
            if (event.type == sf::Event::Closed)
                window.close();
        }
        window.clear();
        window.draw(ball.get_Sprite());
        window.display();
    }

    return 0;
}

ball.h

#ifndef BALL_H
#define BALL_H
#include "SFML\Graphics.hpp"

class Ball
{
private:
        sf::Texture texture;
        sf::Sprite sprite;

public:
        Ball();
        sf::Sprite get_Sprite();
       

};


#endif

ball.cpp

#include "ball.h"
#include "SFML\Graphics.hpp"

Ball::Ball()
{
        texture.loadFromFile("ball_img.png");
        sprite.setTexture(texture);
}

sf::Sprite get_Sprite()
{
        return sprite;
}

The error returned is ball.cpp(12): error C2065: 'sprite' : undeclared identifier.  Thank you.