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 Compute view/proj matrices for head tracking rendering  (Read 3331 times) 0 Members and 1 Guest are viewing this topic.
KaiHH

JGO Kernel

Medals: 820

 « Posted 2017-06-13 21:09:16 »

Ever wondered how you can compute a view and projection matrix given the eye position and any arbitrarily positioned and oriented near plane rectangle, such as what Johnny Lee did with his WiiRemote virtual reality hack using a simple monitor and the WiiRemote? Or do you own a TrackIR device and don't know what to do with it?
It's pretty simple. Here is how:
 1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30  31  32  33  34  35  36  37  38 `/** * Create a view and projection matrix from a given eye position, a given bottom left corner position p of the near plane rectangle * and the extents of the near plane rectangle along its local x and y axes, and store the resulting matrices * in projDest and viewDest. *

* This method creates a view and perspective projection matrix assuming that there is a pinhole camera at position eye * projecting the scene onto the near plane defined by the rectangle. *

* All positions and lengths are in the same (world) units. *  * @param eye *          the position of the camera * @param p *          the bottom left corner of the near plane rectangle (will map to the bottom left corner in window coordinates) * @param x *          the direction and length of the local "bottom/top" X axis/side of the near plane rectangle * @param y *          the direction and length of the local "left/right" Y axis/side of the near plane rectangle * @param nearFarDist *          the distance between the far and near plane (the near plane will be calculated by this method) * @param projDest *          will hold the resulting projection matrix * @param viewDest *          will hold the resulting view matrix */public static void projViewFromRectangle(Vector3f eye, Vector3f p, Vector3f x, Vector3f y, float nearFarDist, Matrix4f projDest, Matrix4f viewDest) {    float zx = y.y * x.z - y.z * x.y, zy = y.z * x.x - y.x * x.z, zz = y.x * x.y - y.y * x.x;    float zd = zx * (p.x - eye.x) + zy * (p.y - eye.y) + zz * (p.z - eye.z);    float zs = zd >= 0 ? 1 : -1; zx *= zs; zy *= zs; zz *= zs; zd *= zs;     viewDest.setLookAt(eye.x, eye.y, eye.z, eye.x + zx, eye.y + zy, eye.z + zz, y.x, y.y, y.z);    float px = viewDest.m00 * p.x + viewDest.m10 * p.y + viewDest.m20 * p.z + viewDest.m30;    float py = viewDest.m01 * p.x + viewDest.m11 * p.y + viewDest.m21 * p.z + viewDest.m31;    float tx = viewDest.m00 * x.x + viewDest.m10 * x.y + viewDest.m20 * x.z;    float ty = viewDest.m01 * y.x + viewDest.m11 * y.y + viewDest.m21 * y.z;    float len = (float) Math.sqrt(zx * zx + zy * zy + zz * zz);    float near = zd / len;    projDest.setFrustum(px, px + tx, py, py + ty, near, near + nearFarDist);}`

This is JOML code, however setLookAt() and setFrustum() are semantically exactly identical to glLoadIdentity() + gluLookAt() and glLoadIdentity() + glFrustum().
orange451

JGO Kernel

Medals: 572
Projects: 9
Exp: 8 years

Your face? Your ass? What's the difference?

 « Reply #1 - Posted 2017-06-14 14:23:35 »

Any sick videos to show it off?

First Recon. A java made online first person shooter!
theagentd
 « Reply #2 - Posted 2017-06-14 14:50:50 »

I may have something to show at some point. =P

Myomyomyo.
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