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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0answers
118 views

FreeGLUT keyboard IO timing and synchronization

Using FreeGLut's keyboard callbacks, glutKeyboardFunc(); glutKeyboardUpFunc(); glutSpecialFunc(); glutSpecialUpFunc(); When in the glutMainLoop pipeline do these functions get called? In other ...
0
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1answer
618 views

LWJGL Adding Textures with VBOs

I'm currently trying to texture a cube, but I am having no luck determining what the next step should be. I can load an .obj model from Blender into my LWJGL program just fine, and I can even make a ...
5
votes
3answers
769 views

What is the purpose of indices in 3D rendering?

Suppose you were creating a 3D cube in OpenGL. You implement the necessary vertex data for the object (cube). What would be the point of using indices? void CreateCube() { ...
1
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1answer
349 views

I can't seem to figure out what's causing this bug with the “layout” keyword in GLSL

I have a GL shader file whose first few lines currently look like this: #version 120 layout (location = 0) in vec3 position; layout (location = 1) in vec2 vertexUV; When I try to compile this ...
1
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1answer
769 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 ...
0
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2answers
218 views

How can I regulate update and event frequency?

I'm trying to create a small 2D RPG-type engine using C++, SDL/OpenGL and Tiled. My little demo looks very similar to a Pokemon or Zelda game. I was curious how to go about regulating FPS and how ...
0
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0answers
98 views

How can I set the attribute index location?

I am trying to set up a shader which takes three input parameters. I have the following code: GLuint vert = glCreateShader(GL_VERTEX_SHADER); GLuint frag = glCreateShader(GL_FRAGMENT_SHADER); const ...
2
votes
2answers
970 views

How can I use ARB_debug_output with SDL on Windows?

I'm trying to port a small GL program that I've been working on from Linux to Windows. I have the following: window_ = SDL_CreateWindow(...); SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS, ...
3
votes
2answers
366 views

Efficient per-frame constants in shaders

I have some variables that stay the same during the entire frame and will be used by a large number of the various shaders I use (several dozens). These include things such as the various transforms ...
15
votes
4answers
2k views

What does a matrix represent?

I began learning OpenGL recently and am having problems visualizing what matrices are and their role in computer graphics. Given the template of a 4x4 matrix like this: I would assume that each ...
-3
votes
1answer
150 views

GLSL does weird things to my view matrix [closed]

uniform mat4 model; uniform mat4 view; varying vec4 vColor; void main(){ gl_TexCoord[0] = gl_MultiTexCoord0; gl_Position = view * model * gl_Vertex; vColor = gl_Color; if(view * ...
1
vote
1answer
940 views

glGetUniformLocation Returns -1

I've been trying to develop shaders that would allow me to easily display text on screen using a font texture. I've previously written shaders that simply drew the text on screen and I passed the ...
2
votes
1answer
169 views

Is it bad-practice using left-handed coordinate system in OpenGL eye-space?

In the engine I am currently programming I want to use a left-handed coordinate system for eye-space instead of the glFrustum standard right-handed one. Is that in anyway considered bad practice?
2
votes
1answer
640 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 ...
1
vote
1answer
168 views

Indirect indexing (uv coords read from texture)

In the vertex shader, I need to make a texture fetch, where the texture coordinate itself is read from some other texture. vec2 uv = texture(someTexture,coords).xy; vec4 val = ...
0
votes
1answer
2k views

FBO blit depth buffer to screen?

I have an FBO in a deferred 4.3 OpenGL renderer, in which I setup the depth buffer of that FBO like this: GLCALL(glGenRenderbuffers(1, &mDepthbuffer)); GLCALL(glBindRenderbuffer(GL_RENDERBUFFER, ...
1
vote
1answer
243 views

glGenBuffers fails with 0x0, win7, glew [closed]

I try to run a simple renderer on my win7 machine but it dies at the first glGenBuffers call. The computer has an Intel HD3000 card, with the latest driver (OpenGL 3.0 support). I use glew 1.10 (self ...
0
votes
1answer
686 views

Import Blender files to SharpGL (openGL for c#) [closed]

please i have problem with import 3D models to SharpGL (openGL in c#). Have you got pls any project where is this problem solved? I need create any models in for example blender, and then import to ...
0
votes
1answer
117 views

Keep rasterized pixel amount constant

I have a scene that is rendered from the point of view of the light using an orthographic projection matrix. For an arbitrarily shaped and oriented object that doesn't change its shape or size in ...
0
votes
1answer
120 views

Is it acceptable to buffer no data OpenGL?

Correct me if I am wrong, but if you call "glBufferData(...)" upon an existing buffer, it will resize the buffer to whatever data you upload. Does that mean if I call something like ...
2
votes
1answer
421 views

Linear filter problem with diagonal lines on adjecent tiles

I am quite new at using OpenGL/GLSL. Basically, the project I am working on is my first 'real' experience with it. I do not know whether this is relevant, but I use libgdx for my project. Currently, ...
2
votes
1answer
265 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, ...
1
vote
1answer
134 views

Telling my shader when to use which Texture

So I've just managed to get Texturing via GLSL shaders to work and i can pass a sampler2d textureHandler + my uv coordinates into my shader to specify the texture to be displayed on my Tiles. Now im ...
2
votes
2answers
1k views

Shadow mapping with directional light?

I'm doing shadow mapping in my OpenGL 4.3 deferred renderer, and I'm starting with directional lights believing it to be the easiest. What I do not understand is how the view projection matrix is to ...
1
vote
1answer
252 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 ...
0
votes
1answer
283 views

Spritefont in OpenGL

I develop in OpenGL using C# as programming language. I want to draw some text on the screen. For this i created a texture that contains all the characters. Now i am not sure how to continue. I can ...
0
votes
2answers
229 views

Pixel perfect clickable picture in OpenGL/C++

So I have a picture(for easier understanding of problem like this: http://www.lib.utexas.edu/maps/europe/europe_95.jpg). My goal is to click on any of the countries and get what country I clicked. ...
8
votes
4answers
426 views

Why nearby triangles tend to disappear?

I've just enabled back face culling and I'm noticing a weird behavior: when all vertices of my triangle is outside the view and 2 of them is behind me (I think) the triangle disappears. So to see it, ...
1
vote
1answer
171 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 ...
0
votes
1answer
506 views

Indexed UV mapping problem [closed]

I am trying to map UV coordinates to indexed vertices with this code. I am using a vertex buffer, texture buffer, and index buffer (note the vertex and texture buffers are indexed in the same order) ...
0
votes
0answers
396 views

2D Sidescroller camera

I'm using OpenGL. For my tiles, I'm using a display list and I'm just using immediate more for my player (for now). When I move the player, I want to center him in the center of the window, but allow ...
13
votes
2answers
2k views

How can I simulate a limited (256) color palette in OpenGL?

On Twitter, I found this screenshot of a game in development: The image on top seems to be without any color limitation. But the two other pictures at the bottom have a 256 color palette. I want ...
1
vote
0answers
79 views

Sampler object not changing texture filter

I am currently binding a sampler object to a texture (GL_TEXTURE12 to be specific) with glBindSampler(12, sampler); and the initial settings are very visible compared to the textures own settings. ...
0
votes
1answer
156 views

Why are some of my normals facing away from the camera?

I'm trying to use WebGL to render some simple models, and I'm running into issues where pixels near the edge of my model are passing normals to my fragment shader that point away from the camera. This ...
3
votes
1answer
1k views

Skeletal animation with Assimp and glm

I'm trying to implement skeletal animation using assimp and glm. Everything seems to work, except for rotations. This is the code I use when packing assimp data into my own engine's format. I THINK ...
-1
votes
2answers
191 views

Models are not rendered correctly. OpenGL

I'm working on my university OpenGL project and as a base of it I'm trying to combine several OpenGL tutorials, mainly tutorials from http://ogldev.atspace.co.uk/. The problem I have is that models ...
1
vote
1answer
162 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 ...
0
votes
1answer
165 views

Linking error at tessellation shaders in GLSL

I'm testing the triangle tessellation from the link http://prideout.net/blog/?p=48#shaders . All the shader are compiled correctly, but when I try to link the program using the command: ...
1
vote
1answer
1k views

What does “GL_CLAMP_TO_EDGE should be used in NPOT textures” mean?

I have two sRGB PNG images I am using for textures. One is 64x64, and works fine. The other is 64x47, and when I attempt to use it I get an error: reason: 'GL_CLAMP_TO_EDGE should be used in NPOT ...
2
votes
1answer
418 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. ...
6
votes
2answers
1k views

Fixed Function vs Programmable Pipeline performance with many batches

In OpenGL 2.0 I can easily make 10,000 draw calls per frame (with state changes in between each call). However, if i try to do this in either OpenGL ES 2.0 or DirectX9 with shaders, my peformance is ...
2
votes
1answer
431 views

LibGDX strange camera behaviour

I'm currently doing my final assessment for my study Game Development. I'm currently facing a real weird (maybe explainable) result from my camera. I just set up my scene with alot of tiles and a ...
9
votes
2answers
2k views

Deferred tiled shading, tile frusta calculation in OpenGL

I'm trying to do deferred tiled shading in OpenGL using the compute shader but I have hit a snag when trying to create the frustum for each tile. I'm using AMD's Forward+ demo (written in D3D) as a ...
1
vote
3answers
875 views

How do I efficiently use 16 bit texture coordinates?

While loading a model I get a big array of 32 bit floating point texture coordinates. I just upload that to a single vertex buffer (along with other data, such as vertices, normals, etc.) and use it ...
1
vote
1answer
102 views

Floating point memory usage on gpu

My question is simple: how much memory on GPU does one floating point value takes? I guess it is 4 bytes, but I'm not sure. So for example is it true that vec4, which holds 4 floats, each 4 bytes ...
2
votes
3answers
302 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 ...
3
votes
4answers
542 views

Dynamic Terrain Triangulation

Is there someone who know/have an algorithm which can perform terrain triangulation like on the example image right under (there is a secondary image as well). The reason I say "Dynamic" is because I ...
0
votes
1answer
2k views

problem using glm::lookAt and glm::perspective

I'm trying to change the code from the 22th tutorial at http://ogldev.atspace.co.uk/, using the GLM library, but the result seems wrong. The problem is shown in the below picture: While it should be: ...
0
votes
2answers
239 views

Flip DDS Texture without original source image for OpenGL

I'm wondering if there's a converter for DDS textures after they've been created. We don't have access to the original source images and we would like to avoid changing our shaders, as I'm told it's ...
0
votes
1answer
290 views

is instanced rendering faster? [closed]

Is instanced rendering used in GLSL faster than doing something like this.. for(int i=0; i<10; i++) { glDrawArrays(GL_POINTS, 0, 3000); } Suppose I want to render 'grass', which is the best ...