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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840 views

OpenGL FBO Rendering

I'm getting some artifacts when I try to use a colour attachment on an FBO. I'm saving my first pass as a texture, then passing it as an input to an anti-aliasing shader. The result is, as below, some ...
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81 views

GLSL to Cg: why is the effect different?

With reference to this question, where I was trying to make the shader compile, I am now trying to make an effect appear. The effect can be shown here, through a GLSL shader: But when I use the ...
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116 views

Should all primitives be GL_TRIANGLES in order to create large, unified batches?

Optimizing modern OpenGL relies on aggressive batching, which is done by calls like glMultiDrawElementsIndirect. Although glMultiDrawElementsIndirect can render a large number of different meshes, it ...
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2answers
82 views

Keeping ratio the same across devices on fixed screen game

My game is an Android game using OpenGL ES 2.0 (But this question could apply to any platform). I have read many questions on here regarding ratio management, and also read many tutorials outside of ...
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1answer
31 views

How should I handle a modelview stack with multiple shader programs involved?

I'm building a framework where each object has an associated program and each object has a 'draw' method. What is the best choice, to have a single modelview stack handled by a Renderer class or to ...
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1answer
39 views

vertex is bending inwards

I am trying to draw a picket fence, but the center of the picket vertex looks bent in the middle, why is the picket bending inwards to the left? // draw fence pickets float a; for (a=-25; a<=25; ...
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1answer
75 views

Gamma Space and Linear Space with Shader

I am using Unity and I can choose between two color space mode in the settings: Gamma or Linear Space. I am trying to build a Custom Lighting Surface shader but I am facing some problems with those ...
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1answer
257 views

How can I implement beam effects like these?

I am interested in the techniques I could use to create the following effects: Can I accomplish this with a particle system or a series of texture quads, or what? You can see this effects in ...
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1answer
128 views

How to save am image of a screen using JOGL

Hope this is a better place to ask things like this. I have a 2D scene with some sprites drawn in Swing frame. I need them to be saved as an image. The problem is every tutorial I found seem to be ...
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1answer
40 views

Having trouble setting color in fragment shader

For some reason, the color isn't applying to the object. Here's my fragment shader code. There's probably something obvious wrong with it that i'm not seeing. #version 330 core out vec3 Color; ...
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1answer
82 views

DirectX Bullet Tracer Effect

I'm wondering if anyone knows some common and efficient ways to do a fast tracer for an instant bullet. I've seen people speak on forums of using primitive lines with DirectX, but I doubt this ...
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1answer
77 views

Is there a way to use other fonts, besides the default ones in OpenGLUT?

I'm using OpenGLUT functions like glutBitmapString to render sentences and words in a game. However, there is a limited set of fonts to use and I need some bigger size fonts. Is there a way to add new ...
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1answer
101 views

Why is the light following my camera around?

I have implemented a simple Phong shader without specular highlights for now (just ambient + diffuse components) The problem however, is that the calculations seem to be done in camera space; as I ...
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1answer
92 views

In glsl, how do indices work?

I have made a vertex shader and fragment shader and kind of know how they work, and I know that you specify what index you want your vertices to be in inside the shader program. So if the vertex was ...
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1answer
235 views

Decoupling rendering pipeline (for UI responsiveness): Multithreading and multiple contexts?

Warning! Wall of text (see <TL;DR> paragraphs below for short version) I have been noticing something in quite many games (most recently in cutting-edge RTS games such as Uber Entertainment's ...
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1answer
128 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 ...
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1answer
340 views

SSAO looks wrong

I'm trying to implement SSAO based on this tutorial. My setup: OpenGL 3.2 Forward renderer View-space depth and normal in a single 16-bit floating point texture. The result I get is this: The ...
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2answers
161 views

How can I compute the orbit of one body around another?

I'm attempting to have a planet (with a known mass and radius) orbit it's sun (also with a known mass and radius). It doesn't have to be 100% realistic, but it should be possible that the sun have ...
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2answers
184 views

gl_FrontFacing - is there perfomance cost?

If I use gl_FrontFacing in my PS, is there any performance cost during vertex transformation (like cross product from triangle vertices), or is this value computed any time ?
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1answer
194 views

How to achieve anisotropic filtering

I am loading a texture and using glGenerateMipmap() on it to achieve some level of mipmaping. I get different result on nVidia gt 555m, and on Intel HD 3000. The texture rendered by nVidia is not ...
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1answer
89 views

Run OpenGL shader on part of a texture

How do I run an OpenGL shader on just a portion of an off screen texture and leave the rest of the texture unmodified? Are there any calls that restrict the sampled pixels to just a rectangle or do I ...
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1answer
134 views

How to enable geometry shader in OpenGL 4.2?

I'm porting my Direct3D-based engine to OpenGL and I'm using geometry shaders for rendering text characters (basically, textured billboards). D3D version works fine, but in OpenGL mode it gives only ...
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1answer
378 views

glGenerateMipmap confusion

I'm trying to get a grip on mipmaps with OpenGL. I believe I understand the concept, but when trying to have OpenGL generate them I wonder how it determines how many mipmaps to generate? Here's what ...
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1answer
182 views

How can I handle errors when there is no valid OpenGL context?

I'm writing cross-platform (iOS, Android, OSX, Windows) library code that draws its output using OpenGL. I expect my users will often try to call my library's rendering functions without a valid ...
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1answer
41 views

Drawing behavior when a fragment is written to multiple times in a single pass

This seems really basic, but I'm confused and can't find a clear answer anywhere. What happens to a target fragment of a rendertarget if the fragment is written to multiple times within one pass ...
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1answer
145 views

How can I extract the RGB color data from a TGA image?

I am working in OpenGL, and I am trying to create terrains using height maps. I am using my own functions to load a TGA image, and in order to pass data to heightmap vertex shader I need to retrieve ...
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1answer
61 views

Models not rendering when far away

I am making a game where objects are represented by colored cubes. I have files that mark the location and rotation of the cubes. I've been using Processing's 3D library and the cubes disappear within ...
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2answers
357 views

OpenGL position from depth is wrong

My engine is currently implemented using a deferred rendering technique, and today I decided to change it up a bit. First I was storing 5 textures as so: DEPTH24_STENCIL8 - Depth and stencil ...
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2answers
767 views

In GLSL is it possible to offset vertices based on height map colour?

I am attempting to generate some terrain based upon a heightmap. I have generated a 32 x 32 grid and a corresponding height map -> In my vertex shader I am trying to offset the position of the Y ...
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2answers
726 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 ...
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1answer
184 views

How to only render part of an image in lwjgl/openGL

I'm making a mining/building game in java using slick2D and I want to make it so you can only see a few blocks in any direction while you are underground. The best example I could find of what I want ...
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1answer
457 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 ...
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1answer
539 views

shadow mapping and linear depth

I'm implementing ominidirectional shadow mapping for point lights. I want to use a linear depth which will be stored in the color textures (cube map). A program will contain two filtering techniques: ...
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1answer
199 views

WebGL immediate mode

I know that WebGL is based on OpenGL ES 2.0 and that glBegin and glEnd have been removed and replaced with vertex buffer objects. I understand that VBOs are faster and use less code but is there a ...
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1answer
698 views

how to make cross platform 3d games using modern opengl? [closed]

How to create games that run on windows, Linux, mac os x, android, ios, wp8 etc.... using c/c++, opengl 3 or 4 and opengl es 2.0. any tutorials or videos on how to create cross-platform 3d games.
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1answer
263 views

Unable to Render to multiple rendertargets

I am trying to implement a simple deferred rendering engine in openGL and i have a little problem with the GBuffer. I cant get it to render to more than one texture at a single time, which is the one ...
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1answer
134 views

Android Object get Jagged at the border

I am new to OpenGL ES 1 in android. My 3D Model border getting Jagged. Please help me to look like a smooth border instead of jagged. Screenshot : http://i.stack.imgur.com/1Gq83.png private class ...
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1answer
508 views

Create a fly camera with lookAt

I want to create a free cam with the lookAt matrix in OpenGL. I just made the control with W, A, S and D so you can move around. But now I nee to look around. I thought doing that with sine and cosine ...
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1answer
418 views

Understanding the z-axis vector from OpenGL modelview matrix

I would like to shoot spheres in the current view direction in a simple scene. I use an FPS camera, so no z-rotation. The vector pointing in the correct direction should be (m[8], m[9], m[10]) where m ...
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2answers
781 views

Changing the sprite position: Modify VBO data or translate it?

I am beginning with VBO and I want to know if it's better use GL_STATIC_DRAW to make a quad and them translate it, or use DYNAMIC_DRAW and modify the vertex position data directly. Also when I modify ...
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1answer
196 views

How to generate texture coordinates for a rectangle?

I've got a function which generates geometry data for a rectangle. So far I've got the vertex, indices and the normals nailed, but I have no idea how to generate the texture coordinates - so far I've ...
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1answer
502 views

Voxel Performance

So Im trying to make a minecraft style voxel game to learn OpenGL, but Im running into performance issues. I found this thread : http://stackoverflow.com/questions/4995652/3d-occlusion-culling where ...
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1answer
154 views

GL_GENERATE_MIPMAP vs. GL_MAX_TEXTURE_SIZE

If we generate mipmaps for a texture using GL_GENERATE_MIPMAP (or glGenerateMipmap), how big can the original texture be? Is it the size returned by GL_MAX_TEXTURE_SIZE, or half of it?
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1answer
434 views

does glBindAttribLocation silently ignore names not found in a shader?

Does glBindAttribLocation silently ignore names that are not found? For example, in a shader: // Some vertex shader in vec3 position; in vec3 normal; // ... And in some set up code: // While ...
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1answer
208 views

OpenGL / Assimp oddity or error?

A friend and I are working on developing a game engine in C++. He doesn't live anywhere near me, so we use Dropbox to sync our files. I opened his project to test his code, and I kept getting errors ...
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2answers
506 views

OpenGL - question about glColorPointer

So, I'm just starting out with LWJGL, and my current task is to render two colored cubes on the screen. I can render them, however, I'm looking for some advice on the most efficient way to specify the ...
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1answer
256 views

Are interleaved vertex data formats better than non-interleaved formats?

I have been reading up on data formatting for 3D objects so that I can render my meshes as fast as possible in OpenGL. I am quite new to OpenGL so bear with me. The format for interleaving your ...
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1answer
2k views

Setting Up GLEW with VS2012 [closed]

I'm trying to set up GLEW with Visual Studio 2012 and I'm having some trouble with it. I downloaded the GLEW binary from http://glew.sourceforge.net/ and moved the contents from it's lib folder to ...
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2answers
158 views

Finding Surface of Inner Volume mesh

I am working on the generation of Hexahedral mesh generation using octree based discretization. I have a volume mesh (Hexahedral), using isomorphism I need to project the outermost surface vertices of ...
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2answers
1k views

Render rotated rectangle inside other rectangle bounds using Libgdx

I have this code to generate a red rectangle inside a grey rectangle: new Rectangle(grey_rectangle_position_x, Game.SCREEN_HEIGHT/2-Rectangle.height/2,0); This code makes the following: Now, I ...