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View Full Version : Can't get my FPS Camera working. WebGL demo and code included.

hashbrown
05-26-2017, 03:30 PM
I'm trying to figure out how to make a fps camera but unfortunately stuck. I'll briefly explain what I'm doing but I'll also share my webgl code so you can see for yourself.

// First I get the difference between the current mouse coords and the last. The html lock cursor api returns it and I store it in Game.Input.

this.yaw += Game.Input.x * this.sensitivity;
this.pitch += Game.Input.y * this.sensitivity;

// I cap the pitch and yaw

if (this.yaw < 0.0) this.yaw += 360.0;

if (this.pitch > 89.0) {
this.pitch = 89.0;
}
if (this.pitch < -89.0) {
this.pitch = -89.0;
}

// This is where I calculate the view matrix and use the pitch and yaw (by the way these are all matrices, JS doesn't really help specifying that)

var view = Mathf.Mat4();

var rotX = Mathf.rotateX(cam.pitch),
rotY = Mathf.rotateY(-cam.yaw),
rot = Mathf.mul(rotX, rotY),
pos = Mathf.translate(cam.x, cam.y, cam.z),

cam = Mathf.Mat4();
cam = Mathf.mul(rot, pos);
view = Mathf.inverse(cam);

return view;

// ... and in my game object draw function, I use the view matrix

model = Mathf.mul(model, scale);
normMat = Mathf.transpose(Mathf.inverse(model));
modelView = Mathf.mul(model, view);
mvp = Mathf.mul(modelView, projection);

Everything works fine, I see the world, I could translate left, right, forward and back if I coded those instructions. But I can't seem to get the mouse look working, I clearly don't understand the fps camera concept properly. I also understand that in order to walk towards the correct direction I'm looking at, I need a few more steps using the cross product, but at the moment I just want to look around and can't seem to get it.

Hope this all makes sense :S Thanks!

WebGL Live Demo: https://jsbin.com/buvugiy/edit?js,output

Oh by the way, I wrote my own Math lib, I'm aware that I could have used any popular one out there, but I wanted to learn. If you want to take a look at it (just in case I did something, wrong) it's here: https://gist.github.com/hashbrownjs/99cc6a175f37991df1e3cdb60f3d8371

I'll go ahead and copy the rotateX and rotateY functions for your convenience since those are crucial in making the cam rotate.

Mathf.rotateX = function (degree) {
var r = Mathf.Mat4(),
cos = Math.cos(angle),
sin = Math.sin(angle);

r[5] = cos; r[6] = -sin;
r[9] = sin; r[10] = cos;

return r;
};

Mathf.rotateY = function (degree) {
var r = Mathf.identity(r),
cos = Math.cos(angle),
sin = Math.sin(angle);

r[0] = cos; r[2] = -sin;
r[8] = sin; r[10] = cos;

return r;
};

Silence
05-27-2017, 09:49 AM
One thing you could try: If you're using the default OpenGL coordinates (x at right, y at top and z going out of the screen), you can try to rotate around x first. Then using the resulted matrix rotate around its y axis vector.

hashbrown
05-29-2017, 09:36 PM
One thing you could try: If you're using the default OpenGL coordinates (x at right, y at top and z going out of the screen), you can try to rotate around x first. Then using the resulted matrix rotate around its y axis vector.

Thanks Silence, I'll give it a try, although I'm going to probably end up re-writing this function again. I want to make sure I understand this concept. I'll definitely share my function here on this thread once I have it ready.