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
729 views

Geometry shader for multiple primitives

How can I create a geometry shader that can handle multiple primitives? For example when creating a geometry shader for triangles, I define a layout like so: layout(triangles) in; ...
5
votes
1answer
853 views

VBO and gl*Pointer management practises?

I'm aware it's not a simple yes/no question and for the moment I can't tell if it can be simply answered, or is it topic for a long discussion which is not suitable for our Q&A format. I want to ...
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1answer
681 views

Difference between the terms Material & Effect

I'm making an effect system right now (I think, because it may be a material system... or both!). The effects system follows the common (e.g. COLLADA, DirectX) effect framework abstraction of Effects ...
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1answer
1k views

Problem with Assimp 3D model loader

In my game I have model loading functions for Assimp model loading library. I can load the model and render it, but the model displays incorrectly. The models load in as if they were using a seperate ...
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votes
2answers
351 views

How does this snippet of code create a ray direction vector?

In the Minecraft source code, this code is used to create a direction vector for a ray from pitch and yaw:' float f1 = MathHelper.cos(-rotationYaw * 0.01745329F - 3.141593F); float f3 = ...
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1answer
1k views

How does one get adjacency information in a geometry shader?

If you use triangle_adjacency as the input type of a geometry shader, do you need to do something on the client side besides make the primitive mode triangle_adjacency? Basically what I'm asking do ...
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votes
2answers
8k views

Does Unity for PC use Direct3D or OpenGL?

I am a mac developer using Unity and I hardly use a PC. When you build a Unity game for Windows, does it use Direct3D or OpenGL? P.S. I'm not sure if it's called Direct3D or DirectX
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votes
4answers
10k views

Wavefront *.obj loader in C++

I'm creating a game using OpenGL (via SDL) and C++ (via Visual Studios 2010 Professional). During the game, I will be using 3D character animation. I'd like to use wavefront *.obj files for all the 3D ...
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votes
1answer
736 views

GLSL shader without a vertex array

Ok so I have a idea for a neat GPU driven curve renderer, and I realised that the vertex shader can be hardwired to generate points of the curve segment (to be rendered as a line strip) without ...
5
votes
1answer
461 views

OpenGL ES 2.0 obscured texture is visible

Hi, I am using LibGDX and OpenGL 2.0 to create a game. So far I have created two meshes. The front mesh is the one with the brown circle texture and another mesh on the top with a green to white ...
5
votes
1answer
355 views

Sprite with alpha Blending in 3D world

I'm working on a game in a 3D world with elements 2D only (Like Don't starve game) for Android and IOS. Currently, I've managed "Sprite" without alpha blending, I've just put a condition in the pixel ...
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votes
1answer
2k views

How to do simple bump mapping

I'm trying to do bump mapping, and I'm getting fairly close at achieving my goal. I miss one crucial piece of my puzzle to have bump mapped effect in my scene; I need to transform the normals from my ...
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1answer
730 views

OpenGL textures loaded with SDL_Image display with no alpha

I am making a game using OpenGL, with SDL_Image employed to load the textures. When drawn on screen, there's no alpha -- in an exact square around the opaque contents of the texture, black is drawn; ...
5
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1answer
6k views

OpenGL ES 2.0: Understanding Perspective Projection Matrix

Setting the Perspective projection matrix in Open GL (including OpenGL ES 2.0) has the following general format: glm::mat4 perspective(float fovy, float aspect, float zNear, float zFar); Notice the ...
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2answers
787 views

Drawing a set of VBOs with one draw command in OpenGL. Is there a glMultiDrawElements for VBOs?

I have a few hundred VBOs, and I want to only draw a subset of the VBOs each frame. Is there anything faster than binding and drawing each VBO? Is there a batched draw command for multiple VBOs? ...
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votes
2answers
262 views

Are display lists faster than VBOs?

I'm making a voxel rendering engine. My "chunks" are 32 * 32 * 256 blocks and I can render a 16 * 16 square of them (which corresponds to Minecraft's maximal render distance). I'm using VBOs holding ...
5
votes
1answer
760 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 ...
5
votes
1answer
141 views

GLImpl.gldrawelements longer than usual

I'm developing a little game engine for the Android platform and I'm trying to improve the performance of this one. (I'm not an OpenGL expert) I can see a framerate drop sometimes, when using DDMS ...
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votes
1answer
2k views

GLSL default shaders

I've been arming my engine with error checking code. I'll try to describe this situation to my best abilities. Whenever i load a shader and there's an error (file doesn't exist, compilation error, ...
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votes
1answer
274 views

Can I leverage the fact that my scene is often static to improve OpenGL (JOGL) performance?

My scene is drawn based on the location of several (often several million) vertices (kept in VBO's) and a camera. I can easily tell in my code when my scene has changed and when it hasn't. There are ...
5
votes
1answer
146 views

How can I implement real-time mutual object reflection?

So, given a scene like this (cubemap skybox with "real" spheres) Everything looks great, except for the fact that the spheres don't reflect each other. What's a good way to go about this? The ...
5
votes
1answer
833 views

What is the recommended way to output values to FBO targets? (OpenGL 3.3 + GLSL 330)

I'll begin by apologizing for any dumb assumptions you might find in the code below since I'm still pretty much green when it comes to OpenGL programming. I'm currently trying to implement deferred ...
5
votes
1answer
174 views

Blend multiple regions from same texture atlas

I'm representing terrain in my game as a grid with at each node a composition, for example 100% rock, or 50% grass, 50% soil. I'd like to use this composition vector to blend textures together. I'm ...
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votes
2answers
2k views

How to rotate camera centered around the camera's position?

Currently I am using gluLook at like so: gluLookAt(position.x, position.y, position.z, viewPoint.x, viewPoint.y, viewPoint.z, upVector.x, upVector.y, upVector.z); with the ...
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votes
1answer
479 views

How to flip a BC6/BC7 texture?

I have some code to load DDS image files into OpenGL textures, and I'd like to extend it to support the BC6 and BC7 compressed formats introduced in D3D11. Since DirectX and OpenGL disagree about ...
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votes
3answers
743 views

Rotate a particle system

Languages / Libraries in use: C++, OpenGL, GLUT Okay, here's the deal. I've got a particle system which shoots out alpha blended textures to produce a flame. The system only keeps track of very ...
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votes
3answers
732 views

Can anyone recommend a 3D model viewer with shading?

I am looking for a simple real-time OpenGL based render engine to show a 3D model on screen. I prefer using 3DS Max's 'shader' materials (real-time materials) for editing. Do you know any good ...
5
votes
1answer
1k views

What's the best way of drawing a glowing 3d line using LWJGL?

Sort of like a strip-light effect; not actually a light source, but just a polygon with glowing edges. Can this be done easily? Right now I'm contemplating drawing a line more than once with varying ...
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votes
2answers
1k views

OpenGL equivalent of .fx files in GLSL or Cg?

There's a lot of learning material in the DirectX world that uses .fx files to manage shaders, and .fx seems to be well integrated with 3D packages such as Maya and 3D Studio Max What do larger ...
5
votes
3answers
325 views

How do I send multiple matrices to a vertex shader?

I'm practising animations using bones/skinning. I am trying to send the shader one matrix per vertex. I can think of these two approaches. Method 1 I have one uniform handle for each bone matrix ...
5
votes
1answer
226 views

Animation of moving circle by square's outer surface

I want to make this animation in OpenGL, here I attached a simple gif how I want it to looks like: Main problem is that I can not figure out how to move by corner - circle should smoothly move by ...
5
votes
2answers
282 views

State of the art Culling and Batching techniques in rendering

I'm currently working with upgrading and restructuring an OpenGL render engine. The engine is used for visualising large scenes of architectural data (buildings with interior), and the amount of ...
5
votes
1answer
573 views

Slow glReadPixels

I have implemented a lense flare for my game, and it looks great. The first draft used individual sprites each with its own draw call. This was very slow, so I reengineered it to use a single draw ...
5
votes
1answer
829 views

OpenGL blending (masking)

I need some help with OpenGL textures masking. I have it working but need to find some other blending function parameters to work in other way. Now I have: //Background ...code... ...
5
votes
1answer
414 views

Raymarching artifacts

I was playing with raymarching using distance fields in GLSL sandbox and got stuck with a strange problem with artifacts. Click here and take a look at the spheres generated in corners, they have ...
5
votes
1answer
295 views

How can I test shaders for nVidia on an ATi system?

I and our other devs have ATi graphics cards. However we have encountered that some shaders that compile without warnings on ATi don't compile at all on nVidia. The problems are trivial to fix, but ...
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votes
2answers
650 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 - ...
5
votes
1answer
191 views

How to pass depth buffer from OGRE to CUDA?

I am using OGRE for rendering some objects. At every frame, I would like to pass the resulting depth buffer to CUDA for running some kernels on it and computing a result. How can I achieve this? How ...
5
votes
1answer
667 views

Bullet Physics implementing custom MotionState class [closed]

I'm trying to make my engine's camera a kinematic rigid body that can collide into other rigid bodies. I've overridden the btMotionState class and implemented setKinematicPos which updates the motion ...
4
votes
2answers
2k views

Lost on OpenGL versions, which to start?

I was reading about OpenGL, and found out the Red Book is a great book for me to read to learn. I then read that even though they have 3.x and 4.x versions, I should still stick to 2.x so I don't ...
4
votes
4answers
667 views

Why do most game devs prefer OGL for OS X and D3D for Windows? [closed]

Today I decided to check what Diablo 3 developers used to do graphics: OpenGL or Direct3D? My mind was completely blown: For Windows, they've used D3D and for OS X they've used OGL. I did some ...
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votes
4answers
5k views

GLM: Euler Angles to Quaternion

I hope you know GL Mathematics (GLM) because I've got a problem, I can not break: I have a set of Eular Angles and I need to perform smooth interpolation between them. The best way is converting them ...
4
votes
3answers
708 views

game models that stand in grass

The open source game Glest has models that feel detached from the ground that they sit on because of the hard edges. In real life, grass is not flat! What are the options and recommendations for ...
4
votes
1answer
4k views

How do I pass vertex and color positions to OpenGL shaders?

I've been trying to get this to work for the past two days, telling myself I wouldn't ask for help. I think you can see where that got me... I thought I'd try my hand at a little OpenGL, because ...
4
votes
3answers
699 views

Voxel engine artifacts

There are white little dots between blocks at random places, mainly at very near blocks. They disappear when I move the mouse and change the view direction. I use Vertex Arrays with ...
4
votes
1answer
1k views

OpenGL datatypes conversion overhead

In my project, certain data is stored in floating point datatypes (C's native float, double). Before sending the data in a VBO to OpenGL I have to convert this data to GLfloat with some pretty silly ...
4
votes
2answers
548 views

What is a reasonable OpenGL version baseline for a mid-range 3D game?

I decided recently write a 3D game in my spare time, as I was tired of my daily "corporate programming". If I expect to be done in 6 months/1 year, which version of OpenGL should I use as baseline? ...
4
votes
2answers
749 views

Optimising the modelview transformation in GLSL for 2D

So, the standard way to transform vertices and then pass to the fragment shader in GLSL is something like this: uniform mat4 u_modelview; attribute vec4 a_position; void main() { gl_Position = ...
4
votes
1answer
2k views

Rendering 2d sprites into a 3d world?

In opengl how do I render 2d sprites in opengl given that I have a png of the sprite? See images as an example of the effect I'd like to achieve. Also I would like to overlay weapons on the screen ...
4
votes
2answers
985 views

Sprite batching in OpenGL

I've got a JAVA based game with an OpenGL rendering front that is drawing a large amount of sprites every frame (during testing it peaked at 700). Now this game is completely unoptimized. There is no ...