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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809 views

Checking Collisions In 2D Platformer With Tiles

My team and I are developing a 2D platformer with C++/SDL/OpenGL, and we already defined a collision system, but we have a problem checking collisions with the tilemap. The tiles of the tilemap are ...
2
votes
1answer
10k views

Rotating an object in OpenGL about it's centre

Im writing a game for which, one of the models are loaded from an .obj file. It's a model of a plane, and I want to rotate the propeller. The object file is broken into groups, and the propeller is ...
2
votes
1answer
3k views

How to convert pixel coordinates to GL coordinates in 2D space?

I know that if you want to display a sprite on screen (in 2D) you can use glOrtho and essentially make 1 gl unit equal to 1 pixel, so when I plot out the vertices for say a 128x128 image (on a quad), ...
2
votes
2answers
179 views

What is the purpose of glEdgeFlagv?

I know that what both glEdgeFlagv and glEdgeFlag do is toggle boundary edge status, but my question is why does the v version exist when the documentation specifies that the only difference is that ...
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3answers
1k views

Mapping rectangular texture on trapezoid-like shape

I have a problem with rendering rectangular textures on non-rectangular surfaces. While googling, I found a thread with person having a pretty similar problem: http://www.gamedev.net/topic/419296-...
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2answers
4k views

Using index arrays with OpenGL VBOs

I've recently started reading about VBOs. If, for example, I want to draw a cube using VBOs, can I use one VBO to hold the coordinates for the 8 vertices, and another one as an index array, to ...
2
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1answer
1k views

Looking for a GUI library for OpenGL, or tips for my own (MetroUI)

I am making an OpenGL graphics accelerated FPS, and I need to find a library to handle GUI correctly. My current GUI handler just wont do! Yes, as in the title says, the UI of the game is Metro (...
2
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1answer
718 views

Beginner question about vertex arrays in OpenGL

Is there a special order in which vertices are entered into a vertex array? Currently I'm drawing single textures like this: glBindTexture(GL_TEXTURE_2D, texName); glVertexPointer(2, GL_FLOAT, 0, ...
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2answers
6k views

Is there any opengl cel shading tutorial out there (without GLAUX)?

I want to implement cel shading into my opengl game. I have only found a nehe tutorial that uses glaux (old as hell). I'm looking into it, but I wanna avoid the pain of learning how to translate those ...
2
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2answers
2k views

3D game special effects, fire, lightning, water, and ice

I'm working on a 3d game using OpenGL and would like to take it in a fantasy direction. Specifically I'm thinking of having magic with effects for fire, water, ice, and lightning. My problem is I ...
2
votes
1answer
65 views

Is there any way in open-gl to “bit crush” everything on the screen?

I am making an educational game and am looking for options for a visual effect to show when something is "incorrect". So, I am looking to see if there's an easy way in openGL to temporarily distort ...
2
votes
1answer
56 views

Polygon edges visible when using per-fragment lighting (OpenGL)

I have created a mesh in Blender (just a sphere with a texture over it; it's supposed to look like mars) and I've exported it as OBJ. I've tried it both with exporting with normals in Blender's export ...
2
votes
1answer
118 views

Finding pitch/yaw values from lookat vector

I have a camera class that contains a position, a pitch, and a yaw (the pitch and the yaw correspond to y and x rotation values). I want to implement a lookAt function that takes a vector and the ...
2
votes
2answers
235 views

MSAA/ CSAA / FXAA How to set the mode in OpenGL?

I'm learning OpenGL and something I am stuck with is AA. Specially when I want to turn it on and off at runtime. I know that I can set the samplecount when I create a FBO and blit it over to the final ...
2
votes
1answer
335 views

GL_DEPTH_COMPONENT vs GL_DEPTH_COMPONENT32

I googled like crazy and checked the OpenGL documentations but I couldn't find out how the precision of a depth buffer created using GL_DEPTH_COMPONENT is chosen. As far as I know the precision is ...
2
votes
1answer
116 views

OpenGL not rendering textures

i'm using OpenGL 2.1 with SDL2.0 and i'm trying to render a texture, using this steps: load the image: Image* image = new Image(); image->image = SDL_LoadBMP(path.c_str()); if (!image->...
2
votes
1answer
126 views

Render scene depth to texture via FBO?

I'm trying to render my scene's depth via FBO and Render To Texture. I have a scene that I'm rendering to a texture, then render that texture to a fullscreen quad in a second pass using a fragment ...
2
votes
1answer
83 views

OpenGL vertex data per index

Usually, vertex data is assigned to a particular vertex, like this: [data] [vertices] [1.31] -> [1, 13, 5] [84.3] -> [5, 8, 12] [.095] -> [8, 3, 10] Then, you would typically have an ...
2
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1answer
349 views

OpenGL picking performance: ray casting vs. color picking

I am curious of how the performance of color picking compares to ray casting. I am looking at the scenario when the mouse is clicked which means only then the scene is rendered in a backbuffer for ...
2
votes
1answer
1k views

OpenGL VBO and VAO Confusion

I would like to present here my Question about VBOs and VAOs. Basically from what i understand you can have different VAOs each of which can contain up to several VBOs , and by binding to the VAO's ID ...
2
votes
1answer
550 views

Why encode floats in RGBA?

Working on some effects that require depth (Z) data in Unity, I saw that these use a method to store the depth data encoded in the RGBA channels of a regular texture. half4 frag(v2f i) : SV_Target { ...
2
votes
1answer
130 views

How can I deal with vertex precision errors between terrain chunks?

I am using OpenGL to render the following scene, using vertex data from one of the map files of a popular MMORPG. The data is chunked and the pictured scene is made up of 256 (16x16) chunks. However ...
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1answer
1k views

2D graphic over 3D perspective projection

To draw a 2D HUD (just a simple trianlge, for now) over 3D graphics in OpenGL I : draw all 3D objects, then call glDisable(GL_DEPTH_TEST) before drawing 2D HUD draw 2D triangle call glEnable(...
2
votes
1answer
478 views

How to improve Batch Rendering to work with 3D skeletal animation data

I've implemented a batch rendering technique that is described in detail here: http://www.gamedev.net/page/resources/_/technical/opengl/opengl-batch-rendering-r3900 I'd like to extend it now to ...
2
votes
1answer
284 views

How can I implement a camera like the one in RotMG?

RotMG, an MMO top-down shooter, takes on a unique 2d-3d style, and has an intriguing camera; The game is obviously 3d, not simply isometric, and if you play the game and turn on camera rotation you ...
2
votes
1answer
573 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 ...
2
votes
1answer
71 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 ...
2
votes
1answer
62 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 ...
2
votes
2answers
413 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 ...
2
votes
1answer
350 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): Pre-update,...
2
votes
1answer
243 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 ...
2
votes
1answer
207 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
1k views

Reflection and shadows in OpenGL

I'd like to implement shadows and reflective surfaces in my OpenGL app. I already have ideas which I will provide below. But I would like to ask someone more experienced than me before I put too much ...
2
votes
1answer
568 views

How to create a regular grid of triangles correctly?

I am trying to create an terrain using opentk/opengl. I have a problem with the VBO/IBO. I think a picture of the problem is the best way to show it: I dont understand why the last triangle of a ...
2
votes
2answers
1k views

3D position to UV coordinates in fragment shader

I am interested in converting an arbitrary 3D position computed at run time in the fragment shader to its corresponding UV coordinates. Notice that the 3D position I am interested in is NOT a 3D ...
2
votes
1answer
2k views

Why do I get “function not supported” exceptions for OpenGL 3.2 functions using LWJGL?

I am currently having an issue trying to initialize a frame buffer using LWJGL. When I try to call GL32.glFramebufferTexture(int, int, int, int) it throws a "Function is not supported" error. I have ...
2
votes
1answer
160 views

Does Direct3D have hardware-dependant extensions like OpenGL?

I am not familiar with Direct3D and I want to know if it has hardware and vendor dependant functions like the extensions in OpenGL? A program written by a friend fails on certain computers while it ...
2
votes
1answer
528 views

Efficient way of loading wavefront models in openGL game

In my game, a RTS game, the units are all wavefront obj. all their animation frames are each seperate wavefront obj file. ie. without any skeletal animation; fully rigid models. So when many units are ...
2
votes
2answers
527 views

Batching and Z-order with Alpha blending in a 3D world

I'm working on a game in a 3D world with 2D sprites only (like Don't Starve game). (OpenGL ES2 with C++) Currently, I'm ordering elements back to front before drawing them without batch (so 1 element ...
2
votes
1answer
991 views

Assimp renders a partial amount of vertices

I'm building a 3D game, and i'm trying to load some assets with the nice Assimp library. The model should look like the one in the first picture, but instead, it takes the form of some kind of avant-...
2
votes
1answer
420 views

Do glColorMask and glDrawBuffer accomplish the same thing?

I'm doing a shadowmap pass (only storing depth values) so I set glDrawBuffer(GL_NONE) to disable color writing for the moment. Yet, I see some tutorials also do glColorMask(GL_FALSE, GL_FALSE, ...
2
votes
1answer
698 views

How can I render a single object that uses multiple textures?

I'm looking for a technique to render an object with multiple texture sources. One texture is static, the other is generated dynamically (it's a render target). For example, say I was rendering a TV. ...
2
votes
3answers
737 views

How can I apply a mesh distortion to walls like in Dungeon Keeper 2?

In Dungeon Keeper 2, the walls of the dungeon have different random shapes depending on its state (freshly dug or reinforced, and so on). They look like they are cubes of 3x3 vertices that have a x-...
2
votes
1answer
696 views

Black or White Border/Shadow around PNGs in SDL/OPENGL

having the same issue as this: Why do my sprites have a dark shadow/line/frame surrounding the texture? however, when I do the fix suggested there (changing GL_SRC_ALPHA to GL_ONE) it just replaces ...
2
votes
2answers
4k views

Drawing multiple objects from one Vertex Buffer Object in OpenGL/OpenTK

I am trying to experimenting drawing method using VBO in OpenGL. Many people normally use 1 vbo to store one object data array. I was trying to do something quite opposite which is storing multiple ...
2
votes
1answer
2k views

Uncharted 2 tone mapping and an eye adaptation

I found an example of uncharted 2 tone mapping on this site. Here is the code: float A = 0.15; float B = 0.50; float C = 0.10; float D = 0.20; float E = 0.02; float F = 0.30; float W = 11.2; float3 ...
2
votes
2answers
364 views

Orthographic Zooming with 0,0 at top/left

I'm trying to implement zooming on my 2D game. Since it's using orthographic projection, I thought it would be easy to implement zooming. After looking around the internet, I found a bunch of ...
2
votes
1answer
105 views

Expandable player boundaries

I'm trying to plan how to implement non-fixed boundaries so the player can expand their controlled territory without using a tiled based system. Each pixel can be fought over for who controls it. I ...
2
votes
1answer
802 views

What happens when a texture is too large for a device

The question is two fold: What happens on a device when a texture is too large for it to handle? Will it crash or simply downsize it? In Unity if I use texture atlases of size 4k and then set ...
2
votes
2answers
217 views

.md5mesh normals are not smooth

I'm currently working on a project that requires me to load .md5mesh format and draw it. Following this link I've managed to load the mesh into the engine successfully, but a problem arises when ...