Camera system

[krystalyamin]

Rubric Items: 1108 (Critical), 1208 (Advanced)

Acceptance Criteria:

• [x] Camera system that allows multiple camera to exist
• [x] Make the camera a component
• [x] Different cameras can be controlled separately

Stretch Goals:

• [ ] Allow multiple cameras to render to the same buffer

[krystalyamin]

References

• Exomata repo
• Hazel repo
• Cherno videos
  • https://youtu.be/ubZn7BlrnTU?si=cgjammjOlFTXC7uq
  • https://youtu.be/8zVtRpBTwe0?si=LpEj0SCTq6yNkL-6

[krystalyamin]

I was debugging an issue where, when the camera was rotated and the viewport did not have a square aspect ratio (i.e. not 1:1), the image would appear stretched.

I tried a few different alternatives to generating my world to view and view to NDC matrices, thinking this was the issue. It turned out that I was just multiplying the world to view and view to NDC matrices in the wrong order. pain.

In order to ensure that all the alt methods I've found don't go to waste, I'm going to immortalize them here.

Manual creation of matrices from Graphics Tutorial 4

    float scaleReciprocal{ 1.f / m_magnification };
    glm::vec2 up{ GetUpVector(r_transform) };
    up *= scaleReciprocal;
    glm::vec2 right{ up.y, -up.x };

    float upDotPosition{ up.x * r_transform.position.x + up.y * r_transform.position.y };
    float rightDotPosition{ right.x * r_transform.position.x + right.y * r_transform.position.y };

    // Update the cached values
    glm::mat4 worldToViewMatrix{
        right.x, up.x, 0.f, 0.f,
        right.y, up.y, 0.f, 0.f,
        0.f,    0.f,   1.f, 0.f,
        -rightDotPosition, -upDotPosition, 0.f, 1.f
    };

    glm::mat4 viewToNdcMatrix {
        2.f / m_viewportWidth, 0.f, 0.f, 0.f,
        0.f, 2.f / m_viewportHeight, 0.f, 0.f,
        0.f, 0.f, 1.f, 0.f,
        0.f, 0.f, 0.f, 1.f,
    };

    return viewToNdcMatrix * worldToViewMatrix;

Using GLM's helper methods

    glm::vec2 up{ -glm::sin(m_orientation), glm::cos(m_orientation) };

    glm::mat4 worldToViewMatrix { glm::lookAt(
        glm::vec3{ r_transform.position.x, r_transform.position.y, 0.f },
        glm::vec3{ r_transform.position.x, r_transform.position.y, -1.f },
        glm::vec3{ up.x, up.y, 0.f }
    )};

    float halfWidth{ m_viewportWidth * 0.5f };
    float halfHeight{ m_viewportHeight * 0.5f };

    glm::mat4 viewToNdcMatrix { glm::ortho(-halfWidth, halfWidth, -halfHeight, halfHeight, -1.f, 1.f) };

    return viewToNdcMatrix * worldToViewMatrix;

[krystalyamin]

As of commit [branch feature-cameraSystem commit 3cadac7]

When the editor windows are active, an internal editor camera is used to render the scene. When the editor windows are toggled off (by pressing ESC), the main runtime camera is used instead.

2 runtime cameras are spawned in the scene when the engine is initialized.

1. The first camera object follows the player object,
2. The second camera stays stationary, but its transform can be adjusted through the component window. Only one runtime camera will be used to render the scene at a time (the "main" camera). You can swap between the two cameras using the Middle Mouse Button.

If debug objects are enabled, objects with camera components will have a purple cross "+" rendered at the position of the camera. The vertical line is oriented to the up vector of the camera, and the horizontal line is oriented to the right vector of the camera.

If no cameras exist in the object list, only the background colour (light brown) will be rendered. There is currently no way to add new cameras to the scene if all the existing cameras have been deleted.

Controls

Editor Camera Control

Control	Action
ESC Key	Close the editor windows and switch the camera to the main runtime camera
Up, Down, Left, Right Keys	Move the editor camera along the world axes
Scroll middle mouse button	Zoom in and out of the scene
Comma Key	Rotate the editor camera counter-clockwise
Period Key	Rotate the editor camera clockwise

Player Controls

Control	Action
W, A, S, D Keys	Move the player along the world axes
Z Key	Rotate player counter-clockwise
X Key	Rotate player clockwise

Runtime Camera Controls

Control	Action
Click middle mouse button	Swap between the two runtime camera objects in the scene
C Key	Zoom the active runtime camera out
V Key	Zoom the active runtime camera in

Nice things to add on in the future:

• Add a button to the camera component that allows the user to pick the camera to be set as the main camera
• Add a button to add camera objects
• Have the editor camera use mouse controls
• Add a way for the user to change the colour of the background
• Add a way to reset Editor Camera Rotation