Java-Gaming.org Hi !
 Featured games (91) games approved by the League of Dukes Games in Showcase (757) Games in Android Showcase (229) games submitted by our members Games in WIP (843) games currently in development
 News: Read the Java Gaming Resources, or peek at the official Java tutorials
Pages: [1]
 ignore  |  Print
 Drawing Polygons and Ellipses using LWJGL  (Read 11599 times) 0 Members and 1 Guest are viewing this topic.
paulo.carabuena

Senior Newbie

 « Posted 2011-12-08 06:59:22 »

hi can anyone help me with this.. i am new to OpenGL.. i'm currently using LWJGL.. actually i am modifying
GTGE interface for LWJGL.. when examining the code, i found that there is no implementation for drawing arcs, circles, etc.

I am confused with how OpenGL works so I find it hard to solve this by myself.. any help is appreciated.. thanks in advance
Bonbon-Chan

JGO Coder

Medals: 12

 « Reply #1 - Posted 2011-12-08 07:56:34 »

OpenGL doesn't any primitive drawing other than point, line, filled triangle and filled quad. (I would say stick with triangle and avoid quad).
For any other shape, you have decompose it :
- line polygon = several lines (easy)
- filled polygon = several triangles (tesselation, see org.lwjgl.util.glu I have never used it but I use my own code for this)
- filled arc and circle can be done with triangles and shader

May be you should take a look to slick2d. It is library over lwjgl that implements a lot of 2d stuff.
theagentd
 « Reply #2 - Posted 2011-12-08 10:02:57 »

To draw a circle, you can use a triangle fans.

 1  2  3  4  5  6  7  8  9  10  11  12  13 `GL11.glPushMatrix();GL11.glTranslatef(x, y, 0);GL11.glScalef(radius, radius, 1);GL11.glBegin(GL11.GL_TRIANGLE_FAN);GL11.glVertex2f(0, 0);for(int i = 0; i <= NUM_PIZZA_SLICES; i++){ //NUM_PIZZA_SLICES decides how round the circle looks.    double angle = Math.PI * 2 * i / SUBDIVISIONS;    GL11.glVertex2f((float)Math.cos(angle), (float)Math.sin(angle));}GL11.glEnd();GL11.glPopMatrix();`

Coded in forum post, there might be typos...

Myomyomyo.
Pages: [1]
 ignore  |  Print

 EgonOlsen (37 views) 2018-06-10 19:43:48 EgonOlsen (20 views) 2018-06-10 19:43:44 EgonOlsen (39 views) 2018-06-10 19:43:20 DesertCoockie (186 views) 2018-05-13 18:23:11 nelsongames (122 views) 2018-04-24 18:15:36 nelsongames (121 views) 2018-04-24 18:14:32 ivj94 (861 views) 2018-03-24 14:47:39 ivj94 (122 views) 2018-03-24 14:46:31 ivj94 (758 views) 2018-03-24 14:43:53 Solater (139 views) 2018-03-17 05:04:08
 Java Gaming Resourcesby philfrei2017-12-05 19:38:37Java Gaming Resourcesby philfrei2017-12-05 19:37:39Java Gaming Resourcesby philfrei2017-12-05 19:36:10Java Gaming Resourcesby philfrei2017-12-05 19:33:10List of Learning Resourcesby elect2017-03-13 14:05:44List of Learning Resourcesby elect2017-03-13 14:04:45SF/X Librariesby philfrei2017-03-02 08:45:19SF/X Librariesby philfrei2017-03-02 08:44:05
 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