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 ...

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2answers
136 views

Best way to detect if vec3 is between vec3(x) and vec3(y) in glsl

As titled I am sampling from a texture and if the color is somehow gray [vec3(.8), vec3(.9)] and an uniform is 1 I need to substitute that color with another one I am not a glsl veteran but I am ...
0
votes
1answer
135 views

Orthographic Projection Issue

I have a problem with my Ortho Matrix. The engine uses the perspective projection fine but for some reason the Ortho matrix is messed up. (See screenshots below). Can anyone understand what is ...
6
votes
1answer
2k views

glDrawElements vs glDrawArrays for polygons that do not reuse vertices

Is it better to use glDrawElements or glDrawArrays when not reusing vertices? There must be some difference, otherwise people would always use glDrawElements? I suppose the question could be ...
0
votes
1answer
177 views

Doing a turntable camera animation on a world matrix rather than view matrix

I have a camera class that contains a 4x4 view matrix as a member variable. Most of my camera controls work fine when doing them directly on the view matrix. In an attempt to unify all of my scene ...
2
votes
2answers
783 views

How to detect graphics API at runtime with SDL2?

Using SDL2, is there a way to determine at runtime whether the application is using OpenGL, OpenGLES, or DirectX? EDIT: If there is a way to figure it out without using the SDL2 API, I'm willing to ...
0
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2answers
266 views

How many normals are needed to have a smooth surface?

I'm trying to draw a smooth cloth surface and I have a per-pixel shader. I expect to have a smooth surface but it's not the case. I think the problem comes from my normals. The image show the surface ...
1
vote
1answer
1k views

How can I prevent the viewport from stretching/distorting?

Basically, I want to know how I can remove distortion or stretching of the rendered image when the viewport/window size changes. The following images exemplify the distortion/stretching I'm talking ...
0
votes
0answers
68 views

GLSL 150 (or upper) per pixel lighting base code

I'm looking for a working example of smooth per pixel shading for one directional light I've seen this example http://www.opengl.org/sdk/docs/tutorials/ClockworkCoders/lighting.php but its old GLSL ...
1
vote
1answer
231 views

Game development for high-school with C++ and OpenGL [closed]

I've been teaching high-school students (12th grade) game programming in the last 2 years. The way I did this till now, was first to give them "half made" classes (for Point, Polygon, etc.) and ...
1
vote
1answer
109 views

Does scaling affect performance in OpenGL? [closed]

I've never been able to understand the best practice in this context. I usually want to ship my game with as minimum size as possible. So whereever possible, I try to use scaling of my graphics. Let's ...
0
votes
1answer
263 views

NiftyGUI - Text isn't rendering

I am trying to create a gui with nifty on top of lwjgl. I've already had some problems during the Nifty setup, however now Nifty is set up and running correctly but for text rendering. Here is my xml ...
5
votes
1answer
895 views

How can glass breaking effect from Smash Hit be achieved? [duplicate]

I saw Smash Hit the other day and was amazed by the physics of the game, specially the shattered glass effect: I've read other posts about this subject but I still feel that they don't share enough ...
2
votes
1answer
60 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 ...
4
votes
1answer
726 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 ...
2
votes
2answers
359 views

Water silhouette shader using GLSL

I have this problem to solve using Cocos2d-x 3.x: In my game there is water represented by rectangle texture, modified by the code on the go. I also have a character moving around, rotating etc. I ...
0
votes
0answers
24 views

Shader | Special Effect - Unit selection [duplicate]

I would like to know how the shaders used to show which unit is selected are made. Here is an image to illustrate. How the merge effect of the blue circles can be achieved ? I didn't found any ...
1
vote
1answer
323 views

Is texture 1D array a valid way to handle object coloring?

I would like to render game UI, and for that I need rectangles. However, since a button could be textured just as well as solid color or (multistop)gradient a problem arises. I would also like all ...
0
votes
1answer
201 views

C++ OpenGL / SDL2 VBO — Depth problem / Transparency

I got a problem with my VBO. When having textures. The far blocks overlay the near ones. I tried editing the alpha, depth buffer, the VBO byte allocation. Nothing works for me... The FAR plane is ...
0
votes
0answers
71 views

Drawing pathmap [Solved]

I am developing an editor for my game and I like to implement something like this (screenshot from wc3 editor): (I need the pathmap) I have one implementation already, I just store in chunk renderer ...
2
votes
1answer
525 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
129 views

Geometry Shader only creates one primitive

I am currently trying to use the geometry shader. My input is a set of points, for which multiple triangle should be created This is the geometry shader #version 330 layout(points) in; ...
1
vote
0answers
500 views

implementing shadows into my 2D GLSL-based lighting system

I'm writing a lighting system in OPENGL using GLSL shaders, and I'm pretty happy with the light casting I have so far, but I'm totally stuck on casting shadows. Everything I've found online on this ...
8
votes
2answers
1k views

How do games handle rendering Asian unicode text?

I'm currently in the process of implementing text rendering in my game engine, and I decided to utilize AngelCode's BMfont to generate font textures, and then have OpenGL render textured quads for ...
0
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0answers
335 views

OpenGL shading doesn't work with different projection and view matrices?

I found an online (public-domain) code to do marching cubes, and I am trying to adapt this code to work in my own project. The code uses GLUT and "older-style" OpenGL, whereas I am using GLM and ...
0
votes
0answers
114 views

Frustum culling - error evaluating a point in the plane of the frustum

I am trying to implement the following code: http://www.lighthouse3d.com/tutorials/view-frustum-culling/geometric-approach-implementation/ I need to use frustum culling in my graphics engine. my ...
1
vote
0answers
165 views

OpenGL ES 2.0 state management best practices [closed]

I use a game engine with dynamic sprite batching for 2D games on mobile platforms (MOAI SDK). It already handles redundant state changes pretty well - with the use of texture atlases it only flushes ...
0
votes
0answers
60 views

Small detail displacement

Hi I am new here so sorry if the question is wrong somehow. I've implemented displacement with tessellation. I tessellate my mesh in the Tessellation Control Shader and then in the Tessellation ...
2
votes
1answer
314 views

GLFW mouselook under OSX

I'm continuing to port an OpenGL app from Visual Studio 2012 to XCode 5. The only major issue I'm having is mouselook. It "doesn't work" under OSX (Mavericks). Here's the (pseudocode): ...
1
vote
1answer
174 views

GLSL Processed Image to OpenGL

I've tried wording and rewording this question in various forms of search and can't seem to find an answer to it. If I'm wording it wrong and/or just not finding the right information, feel free to ...
0
votes
1answer
49 views

transformation before the perspective divide but after projecting perspectively

My problem is that I would like to confine a scene render to a (possibly rotated) rectangle without using glViewport(). I don't want to use it to save, if possible, some cycles that would otherwise be ...
12
votes
4answers
2k views

How can I use the graphics pipeline to render volumetric data based on a density function?

Both graphics APIs (OpenGL and DirectX) devise a well defined pipeline in which several stages are programmable. These programmable stages require to take a fixed minimum amount of data and are ...
1
vote
3answers
235 views

Technique suggestion to render corroded pipes in 3D

We currently have a lot of data relating to cracks/corrosion/deformations in metal pipes which at present, can be viewed in a crude flat/2D application which makes the metal anomalies hard to spot. ...
0
votes
1answer
601 views

lwjgl and slick util text over textured quad

So, I load a TrueTypeFont like this: private TrueTypeFont trueTypeFont; try { InputStream inputStream = ResourceLoader.getResourceAsStream("assets/fonts/main.ttf"); Font ...
0
votes
1answer
205 views

Mesa: Howto enable OpenGL 3.x functionality via extensions?

How can I enable OpenGL 3.x functionality via extensions? I'm new to OpenGL development under Linux. Currently I have: #define GL_GLEXT_PROTOTYPES #include <GL/osmesa.h> #include ...
0
votes
1answer
153 views

Loading non-square textures, from a 256x256 spritesheet in lwjgl(JAVA)

so I'm doing lwjgl, so far I have the loading of 16x16 textures from a 256x256 spritesheet all working, using this code to get the location of the textures: public Vector2f[] calculateUVMapping(int ...
0
votes
1answer
74 views

OpenGL strange rendering problem when buffers have different sizes

I have encountered a very odd error in my program, "odd" in the sense that everything the API says suggests that the error should not occur. I have a bunch of 2D un-indexed vertex data, and I want to ...
1
vote
0answers
66 views

OpenGL seems to be getting its colour from the wrong array on some machines [closed]

I have a OpenSceneGraph application which displays a 2D mesh and allows the user to make selections on triangles and vertices and colour them. If you aren't familiar with OpenSceneGraph, it's basiclly ...
1
vote
1answer
129 views

FBO result not drawing to screen

I recently added framebuffer rendering to my game and rendering to the FBO works (verified with glGetTexImage), but when I go to render a quad to show the result nothing is drawn to the screen. I'm ...
0
votes
2answers
501 views

3D picking for mouse move event

I implemented color picking recently and I would like to use it as kind of highlight when mouse is over an object but I am concerned about performance. Color picking requires whole frame to be drawn, ...
2
votes
1answer
207 views

Additive blending problems

I'm trying to get the blend of two images to work without luck. I have a render target on which I have an object, then I want to render again the same object in same position but with different ...
0
votes
1answer
303 views

What is “ping pong” in the context of graphics rendering?

I have to render a scene, once per light, and blend the result of the various passes. I heard and read that one way to increase performances and render targets to use would be ping pong. I'm new to ...
0
votes
1answer
111 views

Planet terrain not connecting properly

I'm trying to generate some simple planets in OpenGL using libnoise (including noiseutils), but the terrain is not correctly connecting where the sphere "completes itself" and I was wondering if ...
2
votes
1answer
185 views

What types of matrices are needed for game and graphics programming?

I am writing a 3D math library for general game development and want to know what type of Matrix classes I should include. Is just a 4x4 matrix enough, or must I provide 3x4 and dedicated rotational ...
2
votes
1answer
458 views

Indexed Drawing in OpenGL not working

I am trying to render 2 types of primitives- - points ( a Point Cloud ) - triangles ( a Mesh ) I am rendering points simply without any index arrays and they are getting rendered fine. To render ...
4
votes
1answer
225 views

cost of texture change vs color change

How would I go about determining the difference in cost between changing the render color of an object every frame vice changing the texture (same sheet, just changing the source rectangle) every ...
0
votes
1answer
95 views

Can I directly pass a Boost ptr_vector list to glBufferData?

I have a data structure like this: typedef struct vertex_ { float x; float y; float z; float s; float t; }vertex; Then I add to a list called: boost::ptr_vector<vector> vertices; Is there a ...
1
vote
1answer
415 views

OpenGL render to texture causing edge artifacts

This is my first post here so any help would be massively appreciated :) I'm using C++ with SDL and OpenGL 3.3 When rendering directly to screen I get the following result And when I render to ...
3
votes
2answers
584 views

Render with multiple lights (one pass per light)

I have already a system that at the moment handle multiple lights just passing an array of light struct and loop through it. I had been told to switch to a multipass rendering approach. How should I ...
0
votes
2answers
101 views

Taking fixed direction on hemisphere and project to normal (openGL)

I am trying to perform sampling using hemisphere around a surface normal. I want to experiment with fixed directions (and maybe jitter slightly between frames). So I have those directions: vec3 ...
0
votes
2answers
204 views

c++ OpenGL framerate question

I am writing a simple 3D pacman using c++ and OpenGL. I'm new in OpenGL development, I wanted to make a small project before learning next concepts. For now I can't have more than 55fps when ...