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The Most Complicated Camera Code

Pretty self explanatory.

Lv. 46

Yosi

Jul 21, 2020 · 7 min read · 1979 views

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Introduction

It's not very fun to have to build the same camera code over and over each time you make a new project. So I decided to make some camera code that does most things a project would need. It's basically a modified version of Pixelated Pope's simple camera tutorial. It supports smooth camera movement, resizing, rotating, offsets, and screen shake.

Setup

Make sure you have the approach script:

///@func approach
///@args current,goal,amount
return argument0 - clamp(argument0 - argument1, -argument2, argument2);

Make a new object that will control the camera, and paste in all of the following code in the correct events.

The Code

In the Create Event:

enum CAM_TYPE {
linear,
smooth,
}
cam = view_camera[0];
cam_min_x = 0;
cam_min_y = 0;
cam_max_x = room_width;
cam_max_y = room_height;
cam_x = 0;
cam_y = 0;
cam_goal_x = 0;
cam_goal_y = 0;
cam_move_speed = .1;
cam_move_type = CAM_TYPE.smooth;
cam_offset_x = 0;
cam_offset_y = 0;
cam_goal_offset_x = 0;
cam_goal_offset_y = 0;
cam_offset_speed = .5;
cam_offset_type = CAM_TYPE.smooth;
cam_offset_uses_rotation = true;
cam_w = 320;
cam_h = 240;
cam_goal_w = 320;
cam_goal_h = 240;
cam_resize_speed = .1;
cam_resize_type = CAM_TYPE.smooth;
cam_angle = 0;
cam_goal_angle = 0;
cam_rotate_speed = .1;
cam_rotate_type = CAM_TYPE.smooth;
cam_shake_x = 0;
cam_shake_y = 0;
cam_shake_range = false;
cam_shake_ignore_limits = true;
cam_stabilize_speed = 0.1;
cam_stabilize_type = CAM_TYPE.smooth;
cam_round_position = true;
var _window_scale = 2;
window_set_size(cam_w * _window_scale, cam_h * _window_scale);
alarm[0] = 1;
surface_resize(application_surface, cam_w * _window_scale, cam_h * _window_scale);

In the End Step event:

//Resizing
if (cam_w != cam_goal_w || cam_h != cam_goal_h) {
if (cam_resize_type == CAM_TYPE.linear) {
    var _ratio = (cam_goal_h / cam_goal_w);
    cam_w = approach(cam_w, cam_goal_w, cam_resize_speed);
    cam_h = approach(cam_h, cam_goal_h, cam_resize_speed * _ratio);
} else if (cam_resize_type == CAM_TYPE.smooth) {
    cam_w = lerp(cam_w, cam_goal_w, cam_resize_speed);
    cam_h = lerp(cam_h, cam_goal_h, cam_resize_speed);
}
}
//Update Size
camera_set_view_size(cam, cam_w, cam_h);
//Rotating
if (cam_angle != cam_goal_angle) {
if (cam_rotate_type == CAM_TYPE.linear) {
    cam_angle -= clamp(angle_difference(cam_angle, cam_goal_angle), -cam_rotate_speed, cam_rotate_speed);
} else if (cam_rotate_type == CAM_TYPE.smooth) {
    cam_angle -= (angle_difference(cam_angle, cam_goal_angle) * cam_rotate_speed);
}
}
//Update Angle
camera_set_view_angle(cam, cam_angle);
//Movement
if (cam_x != cam_goal_x || cam_y != cam_goal_y) {
if (cam_move_type == CAM_TYPE.linear) {
    cam_x = approach(cam_x, cam_goal_x, cam_move_speed);
    cam_y = approach(cam_y, cam_goal_y, cam_move_speed);
} else if (cam_move_type == CAM_TYPE.smooth) {
    cam_x = lerp(cam_x, cam_goal_x, cam_move_speed);
    cam_y = lerp(cam_y, cam_goal_y, cam_move_speed);
}
}
//Offset
if (cam_offset_x != cam_goal_offset_x || cam_offset_y != cam_goal_offset_y) {
if (cam_offset_type == CAM_TYPE.linear) {
    cam_offset_x = approach(cam_offset_x, cam_goal_offset_x, cam_offset_speed);
    cam_offset_y = approach(cam_offset_y, cam_goal_offset_y, cam_offset_speed);
} else if (cam_offset_type == CAM_TYPE.smooth) {
    cam_offset_x = lerp(cam_offset_x, cam_goal_offset_x, cam_offset_speed);
    cam_offset_y = lerp(cam_offset_y, cam_goal_offset_y, cam_offset_speed);
}
}
//Final Calculations
var _off_x = cam_offset_x;
var _off_y = cam_offset_y;
if (cam_offset_uses_rotation) {
var _len = point_distance(0, 0, _off_x, _off_y);
var _dir = point_direction(0, 0, _off_x, _off_y);
_off_x = lengthdir_x(_len, _dir - cam_angle);
_off_y = lengthdir_y(_len, _dir - cam_angle);
}
var _final_x = cam_x - (cam_w / 2) + _off_x;
var _final_y = cam_y - (cam_h / 2) + _off_y;
_final_x = clamp(_final_x, cam_min_x, cam_max_x - cam_w);
_final_y = clamp(_final_y, cam_min_y, cam_max_y - cam_h);
//Camera Shake
if (cam_shake_range) {
_final_x += irandom_range(-cam_shake_x, cam_shake_x);
_final_y += irandom_range(-cam_shake_y, cam_shake_y);
} else {
_final_x += choose(-cam_shake_x, cam_shake_x);
_final_y += choose(-cam_shake_y, cam_shake_y);
}
if (!cam_shake_ignore_limits) {
_final_x = clamp(_final_x, cam_min_x, cam_max_x - cam_w);
_final_y = clamp(_final_y, cam_min_y, cam_max_y - cam_h);
}
if (cam_shake_x != 0 || cam_shake_y != 0) {
if (cam_stabilize_type == CAM_TYPE.linear) {
    cam_shake_x = approach(cam_shake_x, 0, cam_stabilize_speed);
    cam_shake_y = approach(cam_shake_y, 0, cam_stabilize_speed);
} else if (cam_stabilize_type == CAM_TYPE.smooth) {
    cam_shake_x = lerp(cam_shake_x, 0, cam_stabilize_speed);
    cam_shake_y = lerp(cam_shake_y, 0, cam_stabilize_speed);
}
}
//Update Position
if (cam_round_position) {
_final_x = round(_final_x);
_final_y = round(_final_y);
}
camera_set_view_pos(cam, _final_x, _final_y);

In the Alarm 0 event:
```
window_center();
```

In the Room Start event:

view_enabled = true;
view_visible[0] = true;

How to Use

Goal variables

Set the goal variables to the camera properties you want the camera to end up with eventually.
The speed variables determine how fast the camera properties approach the goal values.
The type variable determines if the camera approaches the goal linearly or in percentages.

Moving the camera around

Set cam_goal_x and cam_goal_y to where you want the camera to look at.
Set cam_round_position if you want the camera position to be pixel perfect.
You can set the camera borders with cam_min_x, cam_min_y, cam_max_x, and cam_max_y. These are the Top Left and Bottom Right coordinates. The example code has the camera restricted to the room borders.

Camera offset

The camera offset is added to the camera coordinates during calculations.
Set cam_offset_x and cam_offset_y to the desired offset.
Setting cam_offset_uses_rotation to true will cause the camera offset to automatically change with the camera angle.

Camera size and window size

Set cam_goal_w and cam_goal_h to the size you want the camera to be.
Try to avoid changing the ratio, as that will mess up how the camera resizes.
Change the value of _window_scale in the Create event to change the size of the window in relation to the cam_w and cam_h.

Rotation

Set cam_goal_angle to the angle you want the view to rotate to.
If you want the camera to immediately rotate, you need to also set cam_angle.
Rotating the camera will allow it to show areas outside the camera borders (cam_min_x etc.), so be careful!

Screen shake

Set cam_shake_x and cam_shake_y to cause the screen to shake.
The amount of screen shake will go back to 0 over time. The cam_stabilize_speed controls how fast this happens.
Setting cam_shake_range to false causes the camera to only move to -cam_shake_x/y or +cam_shake_x/y while shaking. Setting it to true allows the camera to move anywhere in the range of -cam_shake_x/y to +cam_shake_x/y. This setting may be hard to notice.
If you want the camera to be able to go out of bounds while screen shaking, set cam_shake_ignore_limits to true.

That's pretty much all you need to know to use the camera code. Hopefully this helps out some people ;)

The Most Complicated Camera Code

Lv. 46 Yosi

Lv. 46

Yosi