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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1answer
66 views

MVP Matrix * Vector3 = Black Screen? [closed]

I'm relatively new to computer graphics so please take it easy. I created a ModelViewProjection Matrix and I sent it to my shader: #version 330 core layout(location = 0)in vec3 vert; uniform mat4 ...
0
votes
1answer
90 views

Why does my vertex shader produce no output until I add some arbitrary value to the position attribute?

I want to draw a textured quad but there is nothing drawn and the setup should be right. This is my vertex shader: #version 330 in vec2 position; in vec2 texel; out vec2 texCoord; void main() { ...
2
votes
0answers
213 views

Skybox rendering

I am sorry if this is trivial, but I got into OpenGL just very very recently. I am trying to render skybox (with cubemaps) and this is what I have done: Created a VBO with vertices positions (36 ...
0
votes
0answers
137 views

Problems texturing a sphere using a cubemap

I have a single problem which I've attempted two methods to resolve. Neither is giving me 100% results. I've read about 100 tutorials and looked at code but it's just not working out for me; I believe ...
1
vote
2answers
224 views

Weird GLM perspective problems with my 2D Game

I am trying to create the graphics system of a 2D game using OpenGL 3.3. To help me in this task I am using the GLM math libraries. However I am having some trouble. When my objects (for now they ...
1
vote
2answers
215 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 ...
3
votes
0answers
76 views

Are there alternatives to multiple buffering? [duplicate]

I'm learning about game programming. So far, my sources lead me to believe that multiple buffering is the best technique for redrawing in OpenGL. Are there other redrawing techniques? What are their ...
0
votes
0answers
37 views

Using normal maps in irrlicht lime with Direct3D9

I am using Irrlicht Lime, a .NET wrapper for the Irrlicht Engine. In my scene I render some simple geometries, that I construct "by hand". These are textured and shoud get a better look through normal ...
2
votes
1answer
138 views

OpenTK GL.DrawElements is never called

I found this C++ code here. It draws simple rectangle. Works great. #define GLEW_STATIC #include <iostream> #include <glew.h> #include <freeglut.h> const GLchar* vertexSource = ...
0
votes
0answers
72 views

Is it possible to loop over an array of samplerCube/samplerCubeShadow using OpenGL/GLSL?

I try to manage a scene with several point lights. For the moment my program works perfectly with just one point light. So I have in my fragment shader the following uniform declaration: uniform ...
0
votes
1answer
105 views

OpenGL segfault in DrawElements

I've asked this question on regular StackOverflow but without much success yet. The below program produces a segfault on the call to glDrawElements. I've looked at my max and min index values and they ...
1
vote
2answers
262 views

How do I ensure my skybox is always in the background, with OpenGL?

I created a skybox in OpenGL (through LWJGL), but the only way I found to render it behind all objects was to make it very big. This leads to ugly edges between the 6 skybox planes. Optimally, I ...
0
votes
1answer
105 views

New to OpenGL , having trouble understanding matrix transformation

I have modest experience of developing games with sdl , libgdx , unity etc. But never got into learning any low level API. So I thought about learning OpenGL and got started with tutorials provided by ...
1
vote
1answer
151 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 ...
1
vote
1answer
183 views

Architecture to draw many different objects in OpenGL

I have some objects that I want to draw. I am not sure how I can create my architecture in a way where I can draw everything as fast as possible. As example: class MyObject { float[] vertices; ...
0
votes
0answers
27 views

How to get the exact vector location of a loaded model in jMonkey engine

I am new to game developing and using the jMonkey engine. I started to develop an endless running type game. To run, I have created a map with blender and imported it to jME. As the shows, I have ...
2
votes
0answers
58 views

Text rendering overlap

I'm trying to display text with a texture and font description created with BMFont in OpenGL 3.3, but whenever I display the text there is some overlap between certain characters. Here is the text at ...
1
vote
1answer
86 views

Tons of textures using vbo

I recently learned how to create shaders and was looking to make a simple top down game, starting with a tilemap. The problem I encountered, Whilke I can store a vbo of all the blocks in a "chunk" of ...
1
vote
1answer
297 views

How do I add a border to rectangles using a shader?

I want to draw some rectangles with a border. Currently I render the fill with glDrawArrays(Triangles, ...) and the border with glDrawArrays(LineLoop, ...). Is there a neater way? I'm targeting ...
1
vote
1answer
135 views

Correct multiplication order for a 2D Matrix

I'm currently trying to create a camera and entity/model matrix for my 2D game similar to that of Unity3D. I've already tried to find answers to this question on stackoverflow/gamedev but i couldn't ...
3
votes
2answers
145 views

Rendering Many Objects in OpenGL4

Sorry for asking such a basic question. I am reading books on OpenGL4 but in most examples they generally render only objects. So I understand how to deal with vertex buffers and vertex array buffers, ...
6
votes
1answer
211 views

Why does accessing a uniform float make my shader more than twice as slow?

My fragment shader was significantly slowed down by a recent change, and I've been trying to understand why. I isolated the main slow-down to accessing a single particular uniform float. If I include ...
0
votes
1answer
189 views

3D position of an arbitrary UV coordinate

I have a UV map for a 3D mesh that encodes "links" between pairs of UV coordinates. I have previously defined this links (or pairs), one to one. The links are enconded using the function rgb_color(u1, ...
2
votes
1answer
38 views

Swapping Framebuffers or swapping attachments?

I wanted to know what the better approach would be for post-processing: swapping between framebuffers or swapping between textures attached to one framebuffer?
2
votes
2answers
92 views

How to smooth mask texture edges correctly regardless it's size

I have a texture intended as a mask. The texture type is GL_R32F (32 bit float) and the data inside is a signed distance field (= value of each texel is distance to nearest mask edge). For test ...
2
votes
1answer
199 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 ...
1
vote
0answers
38 views

Android OpenGLES, getting number of fragments passed depth test/Occlusion Query?

Afeter reading many blogs and searching on Internet, I did not get any sloution for getting number of fragments/pixels which are occludded or not occludded of the object on OpenGL ES3.0 Android ...
0
votes
1answer
74 views

Applying transformations in Geometry Shader

So, I am trying to program in opengl (3.3) a kind of robot. The idea is that I have some simple blocks that represent his body (4 rectangles for his arms, one for the torso and the last one ...
3
votes
1answer
514 views

OpenGL - Drawing multiple meshes at once using VBOs and IBOs

I have been learning OpenGL 2.1 but using shaders, VBOs, IBOs, etc. I have gotten a rendering engine that can load and draw meshes, materials, forward lighting (no shadows yet), SceneNodes, and ...
1
vote
0answers
120 views

OpenGL - Texture disappears

I'm making a simple program with C++, SDL and GLEW. So far it is going great but I ran into a weird problem. One of my four textures would not show up on screen even though it used the same code as ...
2
votes
1answer
93 views

Selection with region (when rendering with shaders and VAO)

I am currently render my geometry using "Modern OpenGL" approach (with shaders and buffers). I have already implemented picking of single primitives using glReadPixels. Now I am faced with problem how ...
1
vote
1answer
177 views

Draw selected instances of VAO (glDrawArraysInstanced)

I'm using glDrawArraysInstanced to draw multiple instances of a tree at different positions to generate a forest. Is there a way to draw selected instances? For example: I got 100 trees with ...
3
votes
1answer
302 views

glm direction vector rotation

I'm working on a flight simulator, but I'm stuck with my airplane orientation. I tried some things but noone worked correctly. This is what I have : To be able to move it and roll it around himself, ...
2
votes
1answer
59 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 ...
0
votes
1answer
97 views

Blurring part of the screen - optimisation

I develop 3d menu and sometimes I need to blur only part of the screen. I use a forward rendering. I create a frame buffer object with 3 color attachments. Rendering looks like this: bind fbo ...
1
vote
1answer
36 views

Only affect pixels in buffer with alpha 0

I'm working on a transition effect where I have a texture and simply draw that as a pattern to my buffer. Here is a demo, use "e" to start the effect again. This looks fine but it won't work if the ...
0
votes
2answers
134 views

What does glMultiDraw* do?

I'm having trouble understanding exactly what glMultiDraw* does, and when it should be used. Is it to be used if I have one VBO with multiple objects in it or do I use it with many VBO's? It would ...
0
votes
0answers
107 views

Fixing/avoiding Z-fighting with decals OpenGL

I'm trying to draw animated flames as a decal in OpenGL (just a simple quad with an animated texture as a decal on another quad). Problem is as the camera moves away I get terrible Z-fighting in the ...
1
vote
1answer
158 views

OpenGL Compute Shader Uniforms

I am trying to use a compute shader to generate some data in a texture. My compute shader looks something like this: #version 430 //uniform int u_CurrentMipSize; const int u_CurrentMipSize = ...
2
votes
0answers
91 views

problem loading Collada DAE model using Assimp in OepnGL 4.4

I am loading a model in my OpenGL application using Assimp library like this : bool CGameObject::LoadModelFromFile(char* sZFilePath) { std::string fn = sZFilePath; std::string td = "\\"; std::string ...
7
votes
2answers
1k views

How many OpenGL programs should I use to render multiple objects?

My scene has multiple objects in it. (Let's say 3 cubes, 1 cylinder, 8 spheres.) I assume I should create a vertex shader for each. How many programs should I have? Alternatives: One program per ...
1
vote
0answers
186 views

Is it reasonable to use a 2D texture as a lookup table in GLSL

I need a lookup table in a shader. The input values would be color values and the output other color values. Something like: uniform float lut[256]; color = vec3(lut[int(color.r*255.)], ...
5
votes
1answer
232 views

“Normal” Blend Mode with OpenGL Trouble

I've been having a lot of trouble trying to get a OpenGL blend function to work as I'd expect it to with like what I'd expect (or from any sensible image editing program). As an example, I'll use ...
1
vote
1answer
122 views

Lookup table in shader opengl es

What I need is apparently very simple, a lookup table in a fragment shader. It seems that the natural way would be an array float lut[], but in some implementations of OpenGL ES I am getting an error ...
2
votes
0answers
29 views

Render on texture with alpha 0 for the background colour

Sorry if the question is stupid but I am very new to opengl. I render on a target a scene with a couple of object on a background that is nothing more than the clear colour (which is ...
7
votes
2answers
224 views

How to avoid subpixel values in a resolution independent 2D game with orthographic projection?

I'm trying to do resolution independent rendering of moving sprites in a 2D game. My plan is work in a fixed coordinate system in my world (for example 960x540) and use orthographic projection to ...
1
vote
1answer
54 views

Using depth texture for depth testing

I was wondering if it is possible to render my scene onto a depth texture then using that texture for depth testing in another pass. I have an idea to that in shaders, but is that possible ...
0
votes
0answers
80 views

Gaussian blur not working correctly

So pretty much I tried to add a gaussian blur to something I am making and it is acting oddly. The setup is like: [All framebuffers are cleared to rgba(0,0,0,0), normal blend enabled] Draw some solid ...
1
vote
1answer
148 views

Vertex shader in OpenGL/GLSL - transformation of the interior of a textured quad

I have a LWJGL project and ran into a problem with a vertex shader I wrote. In my scene I am rendering a map whose ground consists of rectangular tiles. On top of that there are other objects (I used ...
2
votes
1answer
228 views

Anti-Aliasing in OpenGL [C++]

I'm trying to make anti-aliasing work inside of OpenGL, here's what I've tried: glEnable(GL_POINT_SMOOTH); glHint(GL_POINT_SMOOTH_HINT, GL_NICEST); glEnable(GL_LINE_SMOOTH); ...