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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Set a variable inside a GLSL fragment shader that persists for the render

Is it possible to set a varying variable inside a fragment shader and have it persist? I'd like to use the depth component of the first fragment and use it on all the others, making the fragments all ...
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4answers
2k views

How to pass one float as four unsigned chars to shader by glVertexPointAttrib?

For each vertex I use two floats as position and four unsigned bytes as color. I want to store all of them in one table, so I tried casting those four unsigned bytes to one float, but I am unable to ...
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2answers
5k views

How to implement explosion in OpenGL with a particle effect?

I'm relatively new to OpenGL and I'm clueless how to implement explosion. So could anyone give me some ideas how to start? Suppose the explosion occurs at location $(x, y, z)$, then I'm thinking of ...
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3answers
775 views

Shaders not linking correctly

I'm writing a rather simple "ShaderManager" which aids me with loading shaders in Open GL, altough I am having a few issues: The shaders don't link correctly The the attributes don't bind Here's ...
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2answers
515 views

What is the better approach to redraw a static background scene for game?

Take for an example I have the background scene of a game which should remain static for an interval.Then for every time redrawing the scene,is it better for me to store the color buffer for every ...
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2answers
388 views

Should SIMD be used by people who are new to game development?

I have been learning game development, using C++ and OpenGL, for about 4-5 months. Before that I used to program in C# and the .NET platform(about a year). So, I consider myself new to game ...
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2answers
368 views

Does Blitz3D use its own 3D engine or does it wrap OpenGL?

How does Blitz3D work? I mean internally, does it use OpenGL with basic wrappers or it using some open source 3D engine that itself wraps OpenGL?
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2answers
557 views

OpenGL Camera causes spatial distortion

I'm trying to implement a 3D camera of the "Orbit around the origin" variety in a game engine I'm developing in order to learn about 3D graphics and game programming. I have a basic handle on the ...
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2answers
6k views

OpenGL ES 2.0: Controlling Transparency in Fragment Shader

The following is the OpenGL ES 2.0 simple GLSL Fragment Shader, I use to place textures on polygons, to render 2D sprites. varying mediump vec2 TextureCoordOut; uniform sampler2D Sampler; void ...
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2answers
683 views

Collision Problems

I'm having some troubles with a 2D platformer type game (there's more to it, but that's all that matters for this question). I had collision with the platforms working fine, but if the character hit ...
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3answers
75 views

Rendering many similar objects [closed]

I am writing an city builder. The graphics should look pretty simple, there are no fancy models or textures. Something like Synekism. Thus I have only simple models for buildings and splines for ...
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2answers
82 views

Difference between Spherical Harmonics and Spherical Harmonics Lighting

What is the difference between Spherical Harmonics and Spherical Harmonics Lighting in OpenGL?
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2answers
297 views

C++, OpenGL: Building a polyhedron via geometry shader

I'm stuck with geometry shaders in OpenGL - c++ programming. I want to create simple cube by repeating 6 times drawing one rotated wall. Here is my vertex shader (everyting has #version 330 core in ...
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1answer
99 views

It possible to render a true quad (without triangles) using OpenGL?

Is it possible to render a "true" quad in OpenGL? By that I mean a square which is not made out of two triangles.
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2answers
249 views

How can rotate a 2D textured quad in legacy OpenGL immediate mode?

I have a texture of a tank, and I want to it appearance on the screen depends on its current direction, so I decided to use rotating texture functions of OpenGL. I followed some advices through Google ...
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1answer
86 views

OpenGL - Buffer Usage

I am currently working on a little OpenGL project. At the moment I am trying to find a good solution for rendering multiple objects. I have set up a terrain with its own buffers, which works just ...
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1answer
429 views

Shadow map: depth texture always returns 0

I'm implementing a shadow map for the sun light in my voxel engine using a depth texture attached to a framebuffer. But when I sample the depth texture during the normal pass, the value returned is ...
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2answers
309 views

What dimensions should you use for a perspective projection frustum?

What dimensions should you use for a perspective projection frustum? Initially I created a perspective matrix based on the width and height of the screen, with a calculated zNear value based on a ...
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1answer
309 views

Infinite / Treadmilling Hexagonal Grid

So, I can happily render an infinite square grid by moving said grid whenever the camera moves out of a grid square, auto diff = (cameraTranslation - gridTranslation); bool moveGrid = false; if ...
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1answer
139 views

Does opengl performs Visibilty algorithms based on z-index?

Does OpenGL performs Visibilty algorithms based on z-index? Or we have to write our own algorithms. Mainly I'm referring to z-buffer algorithm. Is it in-built?
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1answer
939 views

Marching Cubes Terrain [closed]

For the past week I've been researching the Marching Cubes algorithm. I hope to use this for Terrain as it would allow the creation of destruction of terrain. After looking at source code and reading ...
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2answers
271 views

LWJGL - If I use VBOs what can I do about separate textures?

So basically this is my problem: I am creating a game that needs a texture for each object. Now I would use a sprite sheet but the textures are different sizes. I am using VBOs and I need to some how ...
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2answers
1k views

Calculate object coordinates from window coordinates using inverse projection matrix

What I am trying to to is placing 3D Objects (A Sphere) in the world when I click there. I am using a perspective projection so the first step after calculating the canonical clip coordinates from ...
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1answer
1k views

How expensive is OpenGL Texture Binding

I'm currently working on a renderer for Tiled's .tmx maps. Among one of the features there is that layers and tilesets are independent, so that a layer can use any tile set on any tile. It's not so ...
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1answer
560 views

Obj Blender Export Recommendation for OpenGL C++

I have been modelling some objects inside blender, like a light bulb. I finished the light bulb, and I got a question at the time of export it. I want to export the light bulb in the wavefront format ...
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2answers
822 views

LWJGL MouseY Coordinates are flipped

So I'm very new to using OpenGL and LWJGL, although I am proficient in Java itself. One of the first things I read in the documentation of the Display class was that it maps the origin to the bottom ...
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1answer
305 views

Using OpenGL GLEW within Unity

Edit:- How do I implement GLEW (or OpenGL extension libraries) within Unity? Original Question:- I've recently been looking into some really nice features of OpenGL 3.2 that I want to take ...
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1answer
2k views

GLSL - rewriting (geometry) shader from #330 to #130 version

I'm having trouble running example from: https://raw.github.com/progschj/OpenGL-Examples/master/07geometry_shader_blending.cpp My graphics card supports only #130 shaders version so I have to rewrite ...
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2answers
10k views

SDL for 3D game programming?

I have been studying SDL for a few weeks and I have succeeded in making a 2D Ping-Pong game, but I want to get started in 3D development, and I'd like to know if SDL is capable (and suitable) for 3D ...
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1answer
945 views

How can I add a parallax effect into my side-scrolling game? [duplicate]

How can I add a parallax effect into my side-scrolling game? I read a lot about parallax scrolling so I know what the logic is and what parallax is but I can't create a dynamic parallax effect. I ...
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2answers
532 views

Chessboard colors with VBO

I am trying to draw a chessboard pattern using VBO. Geometrywise, I have it implemented and working nicely. However, I have come to the point where I want to color up the board and I have realized ...
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1answer
3k views

matrix 4x4 position data

I understand that a 4x4 matrix holds rotation and position data. The rotation data is held in the 3x3 sub-matrix at the top left of the matrix. The position data is held in the last column of the ...
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2answers
3k views

What is an appropriate OpenGL(ES)-based game engine meeting these criteria?

I want to try my hands on a little shooter on the Android platform, and I'm looking for a full-featured 3D game engine. I can't afford to pay more than 400 € for a license, so expensive engines are ...
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2answers
277 views

how could RTT be so slow on my intel card?

I simply draw something into a render target, and use it as an normal texture. It's always working greate to me with my nvidia video card. But today I found my program ran terribly slow (less than 5 ...
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1answer
153 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 ...
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2answers
348 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 ...
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1answer
169 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 ...
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2answers
173 views

OpenGL flickerinng near the edges

I am trying to simulate particles moving around the scene with OpenCL for computation and OpenGL for rendering with GLUT. There is no OpenCL-OpenGL interop yet, so the drawing is done in the older ...
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1answer
138 views

Are there any reasons to use Legacy (2.X) OpenGL?

The benefits are well documented of the Modern OpenGL 3.X & 4.X API's, but I'm wondering if there are ANY benefits to keeping with the old OpenGL, Or if learning OpenGL 2.X is a complete waste of ...
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1answer
174 views

What should I do when a VBO becomes too large in OpenGL?

Currently I have one buffer for my vertex data and one buffer for normals data. I fill them and then pass them to OpenGL for rendering. The problem is when I load too large mesh file like "Lucy" from ...
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1answer
110 views

Given face normal and vertices of a triangle, how to find the acyclic order of vertices?

I'm in the process of constructing a custom 3D triangle mesh. I found the vertices of the triangle in the 3D space and it's face normal. How do I find the acyclic order of vertices? If I draw the ...
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1answer
580 views

How can I calculate a terrain's normals?

Im trying to implement basic lighting in Opengl 3+ (a sun) with this tutorial : http://www.mbsoftworks.sk/index.php?page=tutorials&series=1&tutorial=11 Im building a basic terrain and its ...
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1answer
141 views

opengl offscreen rendering in linux is slow [duplicate]

My opengl application runs at about 110 fps. The moment I add off-screen rendering, it slows down to 15 fps. I am using frame buffer objects and glReadPixels to render off-screen. I have searched on ...
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1answer
149 views

Anisotropic filtering on gbuffer textures for shading pass?

I have a OpenGL 3.3 deferred shader. For my geometry pass I have diffuse textures and/or normal map textures from my models and here I use max anisotropic filtering. But in my shading pass, where the ...
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1answer
325 views

lighting for landscape

I've got a landscape(created in Photoshop .raw file) and a .tga texture for it. I read .raw file and read .tga file like this LoadRawFile("landscape.Raw", MapSize * MapSize, &HeightMap[0][0]); ...
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2answers
579 views

How can I create a VBO when I don't yet know how many vertices it will contain?

I'm trying to convert my 3D block work rendering from immediate mode and display lists to VBOs. I'm having trouble understanding how to properly handle creating the buffers: I really don't know how ...
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2answers
244 views

Why swapping buffers takes different amounts of time?

When my program starts, almost nothing is on screen, just couple of lights and spheres. My FPS is at ~50. The Speed measurements looks like this: UpdateFrame took 0 ms Clearing lights queue: 0 ms ...
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1answer
146 views

SFML image extension for best performance

I am using SFML library in my 2D game. The Texture Class has a method to load an image from file: Texture.loadFromFile("image.*") Which file extension should I use to achieve best performance? ...
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1answer
115 views

What is w componet [duplicate]

What is the W component on graphics programming. I read a blog about opengl that says that w must be equal to either 0 or 1 here. But the book I am currently reading has put w component to more than 1 ...
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3answers
2k views

Replace glTranslatef and glRotatef with matrixes

I'm not an opengl expert, and, as a novice, I prefer to practice a little bit with the old opengl just to be sure to understand correctly the basic concept of computer graphics before deal with ...