Java-Gaming.org Hi !
 Featured games (84) games approved by the League of Dukes Games in Showcase (604) Games in Android Showcase (171) games submitted by our members Games in WIP (654) games currently in development
 News: Read the Java Gaming Resources, or peek at the official Java tutorials
Pages: [1]
 ignore  |  Print
 Perspective calculation  (Read 1466 times) 0 Members and 1 Guest are viewing this topic.
DavidYazel

Junior Devvie

Java games rock!

 « Posted 2003-08-03 04:16:22 »

I am not using GLU for perspective calculation because I need to do my frustum culling with the exact matrix that we use to render.  But I am doing something wrong as it is slightly squishing my perspective from top to bottom.

 1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21 `    public void perspective(float fovx, float aspect, float zNear, float zFar)    {        float sine, cotangent, deltaZ;        float radians = fovx / 2 * (float)Math.PI / 180;        deltaZ = zNear - zFar;        sine = (float)Math.sin(radians);        if ((deltaZ == 0) || (sine == 0) || (aspect == 0)) {            return;        }        cotangent = (float)Math.cos(radians) / sine;        setZero();        matrix.m00 = cotangent / aspect;        matrix.m11 = cotangent;        matrix.m22 = (zFar + zNear) / deltaZ;        matrix.m23 = -1;        matrix.m32 = 2 * zNear * zFar / deltaZ;           }`

Any transformation wizards out there that could point out my mistake?

David Yazel
Xith3D Project Founder
http://xith3d.dev.java.net

It may look complicated, but in the end it is just a bunch of triangles

JGO Wizard

Medals: 16
Projects: 19

Mojang Specifications

 « Reply #1 - Posted 2003-08-03 08:48:58 »

Wild guess; your aspect is inversed? =)

Play Minecraft!
NVaidya

Junior Devvie

Java games rock!

 « Reply #2 - Posted 2003-08-03 09:23:53 »

A fleeting look at my own stuff shows that
if you replace fovX with fovY and treat
aspect ratio as width / height, then your equations
look alright.

Actually, you could just compute w and h and call
glFrustum(...).

HTH

Gravity Sucks !
Orangy Tang

JGO Kernel

Medals: 57
Projects: 11

 « Reply #3 - Posted 2003-08-04 06:00:50 »

Quote

I am not using GLU for perspective calculation because I need to do my frustum culling with the exact matrix that we use to render.

GLU for the most part is simply a set of convinience methods and wrappers that operate on GL. Its perfectly ok to use something like gluPerspective, since it will create the same GL state as if you'd done it manually. glGet will return the same matricies regardless of how you set it up.

You could use gluPerspective with the same numbers and compare the results to see if you're doing it correctly. I'd guess your aspect is wrong. Often an aspect of 1 looks more correct than a properly calculated one..

[ TriangularPixels.com - Play Growth Spurt, Rescue Squad and Snowman Village ] [ Rebirth - game resource library ]
Pages: [1]
 ignore  |  Print

You cannot reply to this message, because it is very, very old.

 SHC (37 views) 2015-08-01 03:58:20 Jesse (24 views) 2015-07-29 04:35:27 Riven (44 views) 2015-07-27 16:38:00 Riven (24 views) 2015-07-27 15:35:20 Riven (27 views) 2015-07-27 12:26:13 Riven (18 views) 2015-07-27 12:23:39 BurntPizza (40 views) 2015-07-25 00:14:37 BurntPizza (48 views) 2015-07-24 22:06:39 BurntPizza (33 views) 2015-07-24 06:06:53 NoxInc (40 views) 2015-07-22 22:16:53
 theagentd 50x wessles 49x basil_ 33x KaiHH 26x orangepascal 25x Riven 22x ags1 17x mooman219 17x bornander 15x KudoDEV 13x klaus 11x princec 11x pquiring 11x CelestialCreator 11x Jesse 9x israelg99 8x
 List of Learning Resourcesby gouessej2015-07-09 11:29:36How Do I Expand My Game?by bashfrog2015-06-14 11:34:43List of Learning Resources2015-05-31 05:37:30Intersection Methodsby Roquen2015-05-29 08:19:33List of Learning Resources2015-05-05 10:20:32How to: JGO Wikiby Mac702015-02-17 20:56:162D Dynamic Lighting2015-01-01 20:25:42How do I start Java Game Development?by gouessej2014-12-27 19:41:21
 java-gaming.org is not responsible for the content posted by its members, including references to external websites, and other references that may or may not have a relation with our primarily gaming and game production oriented community. inquiries and complaints can be sent via email to the info‑account of the company managing the website of java‑gaming.org