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Thread: Mapping Floor Plan Coordinates to Render/3DView Coordiantes

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shmuelzon
Newbie

Israel
Joined: Dec 24, 2023
Post Count: 13
Status: Offline


Re: Mapping Floor Plan Coordinates to Render/3DView Coordiantes

If I'm not mistaken, that code is only the transformation part, i.e., move the target object to the coordinate system of the camera, but the projection itself is done as a part of the renderer's internal code as SH3D provides the lens type, FOV, aspect ratio, etc.
I didn't see the perspective projection part in both renderers but maybe I missed it...

[Jan 13, 2024, 8:00:55 PM]

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Daniels118
Advanced Member

Italy
Joined: Nov 17, 2021
Post Count: 466
Status: Offline


Re: Mapping Floor Plan Coordinates to Render/3DView Coordiantes

Whops, seems you're right... this tells how to compute the projection matrix:
https://gamedev.stackexchange.com/questions/1...atrix-look-like-in-opengl
But you don't need to do it by hand, because Java3D has a ready made mathod for this:
https://download.java.net/media/java3d/javado...ouble,%20double,%20double)
Java3D is embedded in SH3D installation, so you just need to add it to your build path, you don't need to embed it in your plugin.

[Jan 13, 2024, 11:20:36 PM]

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shmuelzon
Newbie

Israel
Joined: Dec 24, 2023
Post Count: 13
Status: Offline


Re: Mapping Floor Plan Coordinates to Render/3DView Coordiantes

I finally got it to work, thanks Daniele!

For future reference, if anyone will stumble upon this post, here's what I ended up with:

int renderWidth = 1024;
int renderHeight = 576;

/* Set up */
Camera camera = getHome().getCamera();
cameraPosition = new Vector4d(camera.getX(), camera.getZ(), camera.getY(), 0);

Transform3D yawRotation = new Transform3D();
yawRotation.rotY(camera.getYaw());

Transform3D pitchRotation = new Transform3D();
pitchRotation.rotX(-camera.getPitch());

Transform3D perspectiveTransform = new Transform3D();
perspectiveTransform.perspective(camera.getFieldOfView(), (double)renderWidth / renderHeight, 0.1, 100);
perspectiveTransform.mul(pitchRotation);
perspectiveTransform.mul(yawRotation);

HomePieceOfFurniture furniture = /* Get some furniture... */;
Vector4d objectPosition = new Vector4d(furniture.getX(), furniture.getElevation(), furniture.getY(), 0);

objectPosition.sub(cameraPosition);
perspectiveTransform.transform(objectPosition);
objectPosition.scale(1 / objectPosition.w);

System.out.println(String.format("Projected pixel: (%d, %d)",
  (int)((objectPosition.x * 0.5 + 0.5) * renderWidth),
  (int)((objectPosition.y * 0.5 + 0.5) * renderHeight)
));

[Jan 15, 2024, 5:59:32 PM]

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