OpenGL is a graphics standard and API which targets the desktop and workstation markets. It is designed to be easy to accelerate with dedicated computer hardware, and hence most implementations give greatly improved performance over traditional software rendering. Currently, OpenGL is used for ...

learn more… | top users | synonyms

2
votes
1answer
152 views

Mouse Speed in GLUT and OpenGL?

I would like to simulate a point that moves in 2D. The input should be the speed of the mouse, so the new position will be computed as following new_position = old_position + ...
1
vote
1answer
133 views

OpenGL (ES 2.0) Function Dependencies

In OpenGL (ES 2.0), there are many functions that can be called in any order, and still others that must be called after other functions had been called and not before. For example, attaching a shader ...
1
vote
1answer
74 views

Architecture to draw many different objects in OpenGL

I have some objects that I want to draw. I am not sure how I can create my architecture in a way where I can draw everything as fast as possible. As example: class MyObject { float[] vertices; ...
0
votes
0answers
16 views

How to get the exact vector location of a loaded model in jMonkey engine

I am new to game developing and using the jMonkey engine. I started to develop an endless running type game. To run, I have created a map with blender and imported it to jME. As the shows, I have ...
1
vote
0answers
73 views

OpenGL - Texture disappears

I'm making a simple program with C++, SDL and GLEW. So far it is going great but I ran into a weird problem. One of my four textures would not show up on screen even though it used the same code as ...
1
vote
1answer
52 views

OpenGL ES draw pre-rendered background onto depth buffer

I want to create a scene with 2D pre-rendered background and 3D models for characters (like those classic Final fantasy games). For the background, I have 2 textures: one to be displayed, with ...
1
vote
1answer
53 views

Tons of textures using vbo

I recently learned how to create shaders and was looking to make a simple top down game, starting with a tilemap. The problem I encountered, Whilke I can store a vbo of all the blocks in a "chunk" of ...
0
votes
1answer
101 views

WebGL wrong scaling of rectangle

I'm working with this tutorial http://www.html5rocks.com/en/tutorials/webgl/webgl_transforms/ and my result is, that the rectangle moves in the direction of it's scaling values, and also scales at ...
2
votes
0answers
40 views

Text rendering overlap

I'm trying to display text with a texture and font description created with BMFont in OpenGL 3.3, but whenever I display the text there is some overlap between certain characters. Here is the text at ...
1
vote
1answer
98 views

How do I add a border to rectangles using a shader?

I want to draw some rectangles with a border. Currently I render the fill with glDrawArrays(Triangles, ...) and the border with glDrawArrays(LineLoop, ...). Is there a neater way? I'm targeting ...
3
votes
1answer
764 views

exporting bind and keyframe bone poses from blender to use in OpenGL

EDIT: I decided to reformulate the question in much simpler terms to see if someone can give me a hand with this. Basically, I'm exporting meshes, skeletons and actions from blender into an engine ...
6
votes
2answers
748 views

atmospheric scattering and sky geometry

I'm trying to implement an atmospheric scattering in my graphics (game) engine based on the gpu gems article: link. An example implementation from that article uses a skydome. My scene is different - ...
-1
votes
0answers
22 views

changing the color of gl_quads inside loop

I am trying to make a chess board with black and with quads , it should display black and whiote alternate quards but its not doing that for some reason here is my code #include <glut.h> void ...
0
votes
2answers
51 views

How would I start my multiplayer game? (JAVA) [on hold]

I'm Bryce. I'm trying to create an online game. To give you an idea on what scale I am imagining this game to be at, I'm basically recreating Notch's cancelled game, 0x10c. I'm here to ask: where ...
1
vote
1answer
55 views

Correct multiplication order for a 2D Matrix

I'm currently trying to create a camera and entity/model matrix for my 2D game similar to that of Unity3D. I've already tried to find answers to this question on stackoverflow/gamedev but i couldn't ...
3
votes
2answers
138 views

Possible to create transparency shader which doesn't stack alpha values

The image above best demonstrates what I'm trying to achieve. It's a transparent shader for objects, but wherever the objects with this shader intersect they don't add together but simply merge with ...
1
vote
1answer
159 views

Random lines away from images in java2d opengl game

Working on a java game that uses some pngs images for icons/textures. A few images ( fewer than 5, out of dozens ) are showing some odd parallel "artifact" lines. They move with the image, are ...
0
votes
1answer
83 views

3D position of an arbitrary UV coordinate

I have a UV map for a 3D mesh that encodes "links" between pairs of UV coordinates. I have previously defined this links (or pairs), one to one. The links are enconded using the function rgb_color(u1, ...
3
votes
2answers
94 views

Rendering Many Objects in OpenGL4

Sorry for asking such a basic question. I am reading books on OpenGL4 but in most examples they generally render only objects. So I understand how to deal with vertex buffers and vertex array buffers, ...
5
votes
1answer
939 views

Exponential Variance Shadow Mapping - implementation

I use a variance shadow mapping with a "standard" light bleeding fix in my graphics engine which is based on deferred rendering.. I have a single shadow map for a directional light beacause a test ...
1
vote
1answer
90 views

How to implement camera pan like in Maya?

I am trying to implement camera pan like the one in Maya. I've got it almost working. The problem is that the mouse cursor is moving faster than the 3d mesh (in fact I am moving the camera but I ...
1
vote
1answer
214 views

Calculating shadowmap coordinates for cubemap in shading pass?

I'm trying to implement shadow mapping with cube maps. I believe I've done the first stage by filling the cube map, but for the final shading pass I am unsure how to exactly calculate the cubemap ...
3
votes
0answers
65 views

Why does accessing a uniform float make my shader more than twice as slow?

My fragment shader was significantly slowed down by a recent change, and I've been trying to understand why. I isolated the main slow-down to accessing a single particular uniform float. If I include ...
2
votes
1answer
24 views

Swapping Framebuffers or swapping attachments?

I wanted to know what the better approach would be for post-processing: swapping between framebuffers or swapping between textures attached to one framebuffer?
2
votes
1answer
127 views

Use different values for Depth Test and Depth Write in OpenGL

Is there a way to use something similar to PolygonOffset to make a depth test more permissive (move fragment depth towards eye) but still write the original depth value to the depth buffer? The only ...
2
votes
2answers
53 views

How to smooth mask texture edges correctly regardless it's size

I have a texture intended as a mask. The texture type is GL_R32F (32 bit float) and the data inside is a signed distance field (= value of each texel is distance to nearest mask edge). For test ...
1
vote
0answers
13 views

Android OpenGLES, getting number of fragments passed depth test/Occlusion Query?

Afeter reading many blogs and searching on Internet, I did not get any sloution for getting number of fragments/pixels which are occludded or not occludded of the object on OpenGL ES3.0 Android ...
0
votes
1answer
42 views

Applying transformations in Geometry Shader

So, I am trying to program in opengl (3.3) a kind of robot. The idea is that I have some simple blocks that represent his body (4 rectangles for his arms, one for the torso and the last one ...
0
votes
1answer
156 views

translate-scroll repeated 2d texture using opengl shader

I managed to implement an infinite 2d texture scrolling using the following shader. btw I'm using cocos2d-x 2.2.1. The vertex shader: attribute vec4 a_position; attribute vec2 a_texCoord; #ifdef ...
1
vote
1answer
115 views

glOrtho setting view

I am duplicating this thread from stackoverflow, please remove it if that is not allowed. I'm completely new in OpenGL. I have this problem: I have quite a complicated scene, and I am looking at it ...
2
votes
1answer
34 views

Rendering a mesh in image viewport

I have a mesh made of nearly half to a one million vertices. I also have some 6-DoF camera poses around this mesh. At these poses I'd like to find out which of the 3D points of this mesh get projected ...
15
votes
4answers
2k views

Why do we use 4x4 matrices to transform things in 3D?

To translate a vector by 10 unit in the X direction, why do we have to use a matrix? We can just add 10 to the mat[0][0], and we got the same result too.
3
votes
1answer
69 views

OpenGL - Drawing multiple meshes at once using VBOs and IBOs

I have been learning OpenGL 2.1 but using shaders, VBOs, IBOs, etc. I have gotten a rendering engine that can load and draw meshes, materials, forward lighting (no shadows yet), SceneNodes, and ...
7
votes
2answers
174 views

How to avoid subpixel values in a resolution independent 2D game with orthographic projection?

I'm trying to do resolution independent rendering of moving sprites in a 2D game. My plan is work in a fixed coordinate system in my world (for example 960x540) and use orthographic projection to ...
3
votes
1answer
91 views

glm direction vector rotation

I'm working on a flight simulator, but I'm stuck with my airplane orientation. I tried some things but noone worked correctly. This is what I have : To be able to move it and roll it around himself, ...
1
vote
1answer
50 views

Selection with region (when rendering with shaders and VAO)

I am currently render my geometry using "Modern OpenGL" approach (with shaders and buffers). I have already implemented picking of single primitives using glReadPixels. Now I am faced with problem how ...
1
vote
1answer
67 views

Draw selected instances of VAO (glDrawArraysInstanced)

I'm using glDrawArraysInstanced to draw multiple instances of a tree at different positions to generate a forest. Is there a way to draw selected instances? For example: I got 100 trees with ...
3
votes
6answers
3k views

Can I develop Linux + Windows games using C#, .NET and OpenGL?

I want to learn to develop 3D and 2D graphics with either OpenGL or DirectX. I chose OpenGL as it's being used in webGL and works cross-platform. I already know .NET well, and the C# language just ...
2
votes
2answers
469 views

How do I apply 2 rotations about different points to a single primitive using OpenGL

I'm working on a 2D top-down shooter game that has a rotation feature like Realm Of The Mad God such that if you press e the camera rotates around the character in a clockwise direction and q rotates ...
1
vote
2answers
220 views

How are red dot/reflex/holographic sights implemented?

In first-person-shooters like Call of Duty, the hologram only appears when it is behind the glass portion of the sight. In OpenGL, would it be implemented by rendering the glass to the stencil buffer ...
2
votes
1answer
52 views

How to know when graphics driver or card changes

I'm about to start work on implementing GLSL binary shader compilation and I was curious how to handle the cases when the shaders need to be recompiled, such as when the driver (or perhaps even the ...
0
votes
0answers
26 views

High-Performance Concurrent Model-View Rendering Architecture [migrated]

I have a single-threaded file indexing/scanning engine in D I want to extend with a view thread that visualizes the scanned content as a tree (or later force-directed graph). I want this solution to ...
5
votes
1answer
122 views

How to implement translation, scale, rotation gizmos for manipulating 3D object's transforms?

I am in the process of developing a basic 3D editor. It uses OpenGL for rendering a 3D world. Right now my scene is just a few boxes of different sizes and I am at the stage where I want to be able to ...
0
votes
1answer
84 views

Blurring part of the screen - optimisation

I develop 3d menu and sometimes I need to blur only part of the screen. I use a forward rendering. I create a frame buffer object with 3 color attachments. Rendering looks like this: bind fbo ...
4
votes
1answer
132 views

How to calculate directional light frustum from camera frustum

I'm playing around with OpenGL for a few weeks now. For the following screenshot I picked the glm::ortho values for my lightsource by trial and error. There are two directional light sources with ...
3
votes
2answers
1k views

FBX Importer - Texture Name

I have a problem with the FBX SDK. I read in the data for the vertex position and the uv coordinates. It works fine, but now I want to read for each polygon to which texture it belongs, so that I can ...
1
vote
1answer
30 views

Only affect pixels in buffer with alpha 0

I'm working on a transition effect where I have a texture and simply draw that as a pattern to my buffer. Here is a demo, use "e" to start the effect again. This looks fine but it won't work if the ...
5
votes
1answer
140 views

“Normal” Blend Mode with OpenGL Trouble

I've been having a lot of trouble trying to get a OpenGL blend function to work as I'd expect it to with like what I'd expect (or from any sensible image editing program). As an example, I'll use ...
0
votes
2answers
80 views

What does glMultiDraw* do?

I'm having trouble understanding exactly what glMultiDraw* does, and when it should be used. Is it to be used if I have one VBO with multiple objects in it or do I use it with many VBO's? It would ...
0
votes
0answers
47 views

Fixing/avoiding Z-fighting with decals OpenGL

I'm trying to draw animated flames as a decal in OpenGL (just a simple quad with an animated texture as a decal on another quad). Problem is as the camera moves away I get terrible Z-fighting in the ...