Shooter Game Player Rotation Help

beginners
#1

Hello I am creating a little top down 2D game and I am trying to have my player aim his gun towards my mouse position so the direction of the gun will aim towards the mouse position. I thought I had it all figured out but it just made my game screw up even more.

void Player::draw()
{
	//Player

	ofPushMatrix();

	ofTranslate(500, 500);

	ofFill();
	ofSetColor(playerColor);
	ofDrawCircle(x, y, r);

	ofNoFill();
	ofSetLineWidth(3);
	ofSetColor(0, 0, 0);
	ofDrawCircle(x, y, r);

	ofFill();
	ofSetColor(0, 0, 0);
	ofDrawRectangle(x - 5, y + 25, 10, 25);

	ofRotate(theta);

	ofPopMatrix();
}

void Player::update()
{
	xDistance = ofGetMouseX() - x;
	yDistance = ofGetMouseY() - y;

	theta = atan2(yDistance, xDistance) * 180 / PI;
}
#2

Hi!
Here’s a working demo:

void ofApp::setup(){
    x = 0; y = 0; r = 10;
}

void ofApp::draw(){
    ofPushMatrix();
    ofTranslate(300, 300);
    ofRotateDeg(theta - 90);
    
    ofFill();
    ofSetColor(ofColor::red);
    ofDrawCircle(x, y, r);
    
    ofNoFill();
    ofSetLineWidth(3);
    ofSetColor(0, 0, 0);
    ofDrawCircle(x, y, r);
    
    ofFill();
    ofSetColor(0, 0, 0);
    ofDrawRectangle(x - 5, y + 25, 10, 25);
    
    ofPopMatrix();
}

void ofApp::update(){
    float xDistance = ofGetMouseX() - 300;
    float yDistance = ofGetMouseY() - 300;
    
    theta = atan2(yDistance, xDistance) * 180 / PI;
}

When calculating the distance you should take the absolute position of the player, so take the translation into account.
And rotate before drawing :slight_smile:
I would save the position into a vector
ofVec2f pos;
In draw()
ofTranslate(pos.x, pos.y);
In update(){
float xDistance = ofGetMouseX() - pos.x; // Etc

#3

I would really discourage you to move things using ofTranslate, popMatrix and pushMatrix, it is a bad practice that can lead you to a lot of bugs. Use vectors, move things around using vectors and calculate directions using vectors. This is the best introduction you can find online about vectors https://natureofcode.com/book/chapter-1-vectors/, @superartificial ported all the nature of code to OF a while ago https://github.com/superartificial/Nature-Of-Code-Open-Frameworks-Port/tree/master/Nature%20Of%20Code%20OF, unfortunately it is a bit outdated and it uses ofVec3f instead glm::vec3.
For a more concrete exampe of something moving towards the mouse position using glm::vec3, have a look at this https://github.com/edap/udk-2019-creative-coding/tree/master/03-vectors-circle.

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