point of collision

[ghost]

trafficstars

Hello ! How can i found position of collision when is it true ?

also i need normal direction .

[jeffThompson]

Getting the point of collision would be super easy for some of these (point/point, for example) but very difficult for most of them. The math gets way more complex and the code would be quite a bit slower, which is why the positions of collision isn't included here, sorry!

For normal direction, you mean the direction that the object was moving when it collided with another?

[ghost]

When I saw this example

Line - Line Or Line Rectangle

I could not find the code for the red points, so I asked this question. It would be helpful if I could talk about what I want to make!

Ray cast hit : in 2D I want to find out between two points with a line which is the closest object and where this point collides and what is its direction.

I think this method will have a quick result

The red dot source code is very useful to me and solve all

:1st_place_medal: Your code is very simple to learn and great!

[jeffThompson]

Ah, those will actually be really easy! If you look in the collision functions, they give us the x/y coordinates. I don't send them back to the main draw() but you could definitely modify the function to return a vector instead of true/false.

For example, here's line/line:

// LINE/LINE
boolean lineLine(float x1, float y1, float x2, float y2, float x3, float y3, float x4, float y4) {

  // calculate the distance to intersection point
  float uA = ((x4-x3)*(y1-y3) - (y4-y3)*(x1-x3)) / ((y4-y3)*(x2-x1) - (x4-x3)*(y2-y1));
  float uB = ((x2-x1)*(y1-y3) - (y2-y1)*(x1-x3)) / ((y4-y3)*(x2-x1) - (x4-x3)*(y2-y1));

  // if uA and uB are between 0-1, lines are colliding
  if (uA >= 0 && uA <= 1 && uB >= 0 && uB <= 1) {

    // optionally, draw a circle where the lines meet
    float intersectionX = x1 + (uA * (x2-x1));
    float intersectionY = y1 + (uA * (y2-y1));
    fill(255,0,0);
    noStroke();
    ellipse(intersectionX,intersectionY, 20,20);

    return true;
  }
  return false;
}

And this is the part you want!

float intersectionX = x1 + (uA * (x2-x1));
float intersectionY = y1 + (uA * (y2-y1));

[ghost]

Thank you very much, even very simple things can be useful 😃👍

On Wed, Mar 2, 2022, 8:04 PM Jeff Thompson @.***> wrote:

Ah, those will actually be really easy! If you look in the collision functions, they give us the x/y coordinates. I don't send them back to the main draw() but you could definitely modify the function to return a vector instead of true/false.

For example, here's line/line:

// LINE/LINE boolean lineLine(float x1, float y1, float x2, float y2, float x3, float y3, float x4, float y4) {

// calculate the distance to intersection point float uA = ((x4-x3)(y1-y3) - (y4-y3)(x1-x3)) / ((y4-y3)(x2-x1) - (x4-x3)(y2-y1)); float uB = ((x2-x1)(y1-y3) - (y2-y1)(x1-x3)) / ((y4-y3)(x2-x1) - (x4-x3)(y2-y1));

// if uA and uB are between 0-1, lines are colliding if (uA >= 0 && uA <= 1 && uB >= 0 && uB <= 1) {

// optionally, draw a circle where the lines meet
float intersectionX = x1 + (uA * (x2-x1));
float intersectionY = y1 + (uA * (y2-y1));
fill(255,0,0);
noStroke();
ellipse(intersectionX,intersectionY, 20,20);

return true;

} return false; }

And this is the part you want!

float intersectionX = x1 + (uA * (x2-x1)); float intersectionY = y1 + (uA * (y2-y1));

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