We can project all the vertices of the cube into camera space. But at what distance from the camera will the projection of the top point be equal to 1, and the bottom -1?

Yes, it’s possible - I actually used a somewhat similar method to calculate at which distance from my globe I should place the camera so that the globe is in full view, i.e. it occupies the entire viewport. The key to such calculations is an appropriate version (according to the shape of the object)…

Thanks. Can you show the formula for a cube without changing the rotation of the camera and its fov, just for the distance (given that the camera can look at the cube at an angle)?

Ah, I see. It seems I misundertood your objective - I thought you only wanted the initial (vertical) apparent size of the cube to be from y = -1 to y = 1 in camera space, but it seems you want to continuously adjust the camera distance (without altering its FOV or rotation) so that the cube vertical…

Using a simple vertex projection is not suitable, because when the distance changes, the visible FOV and the proportions of the object change. So it would just work for an orthogonal camera. It’s not a linear relationship, which is why I asked the question. A good example that shows that the size o…

An object will visually fit into the canvas dimensions if it fits into the camera frustum (and the camera is setup to use the whole canvas for rendering). For a perspective camera, the ratio of half-height of the frustum to the distance is equal the tangent of the half of FOV angle: h/d = tan(fov/…

But what if the plane of the camera is not parallel to the plane of the side of the cube? https://upload.wikimedia.org/wikipedia/commons/5/5f/Blender-mesh-cube.png

You’ll need to find the biggest size (horizontally and/or vertically) of the cube in its cross-section that’s parallel to the camera planes (and fit that into the frustum). The answer depends on how exactly you’re rotating the cube in 3D space: around which axes by what degree etc.

[image] womas: Using a simple vertex projection is not suitable, because when the distance changes, the visible FOV and the proportions of the object change. So it would just work for an orthogonal camera. It’s not a linear relationship, which is why I asked the question. Technically, when it…

The camera can be rotated in any way. Can you show the code that calculates the distance for a rotated perspective camera that would fit the cube perfectly into the height of the screen? On the example of this cube with dimensions 1x1x1. https://upload.wikimedia.org/wikipedia/commons/5/5f/Blender-…

That is, I am looking for an analytical code / approach that will take into account perspective distortions and ensure that the object is visually fitted on the screen. Not just fitted in frustum, but fitted so that the top pixel is on the top border of the canvas, and the bottom pixel is on the bot…

Is it possible to know at what distance of the camera from the cube the height of the perspective projection of the cube will be equal to the height of the screen?

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Fyrestar September 11, 2022, 3:27pm 21

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Is it possible to know at what distance of the camera from the cube the height of the perspective projection of the cube will be equal to the height of the screen?

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