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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1k views

Draw quad with OpenGL VBO using OpenTK

I'm trying to learn how to use VBO (Vertex Buffer Objects) by putting together a simple program that draws a quad to the screen using OpenTK (C# OpenGL bindings). Unfortunately I'm not seeing ...
0
votes
1answer
222 views

VBO in a class doesn't draw when The class has a destructor

I am making this class QuadTemplate class QuadTemplate { public: QuadTemplate() { vbo=0; uvbuffer=0; vao=0; TextureID=0; vboType=0; ...
3
votes
1answer
920 views

How to program dynamic touch events that scale according to device?

When using openGL to build a UI for my prototype I find that that I am still required to use pixels to capture touch events. To make matters worse the Android Docs make this subject slightly ...
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0answers
587 views

Creating a new GLFW window and re-using the old context causes crash

I am using GLFW 3.0.2 and when I want to switch the application to fullscreen, I create a new window and intend to use the OpenGL context of the old window so I don't have to reload all the meshes, ...
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1answer
2k views

Parsing Blender obj with Opengl And C++

I wrote an example attempting to parse blender *.obj file in OpenGl/C++ , to get it done : I have to open the file, exploding it's lines ...and returning the result. This is how the shape.obj file ...
2
votes
0answers
98 views

How do I calculate the points of a brush from a Source engine VMF? [closed]

I'm trying to render the brushes from a Source engine .vmf file in C++, using OpenGL. The .vmf stores solid brushes as a series of planes which I would like to use to calculate the points for each ...
3
votes
2answers
4k views

Rotating an object when the center in not the origin - opengl

I'm beginning with GLSL and I learning the basic, I am using glm to do the matrix calculations at this point everthing ok,the problem is how I can move the origin to the center of my object, not the ...
3
votes
1answer
298 views

Directional light shader not behaving as expected

I coded my first glsl shader which manage diffuse and specular effects of a directional light. This is the fragment shader. #version 120 //matrix uniform mat4 model_matrix; //directional light ...
0
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1answer
193 views

Textures not rendering with VBOs

After having used display lists for my programs since I started learning OpenGL, I've finally decided to switch to VBOs after experiencing a considerable amount of lag when I started work on a new ...
7
votes
2answers
6k views

GLSL Shader - Change Hue/Saturation/Brightness

I'm trying to change the hue of an image using a GLSL fragment shader. I want to achieve something similar to Photoshop's Hue/Saturation Adjustment layer. In the following image you can see what I've ...
1
vote
0answers
214 views

GLX/X11 Changing the rendering resolution

I have made a simple application that creates a window with an OpenGL 4.2 context and takes user input. I have implemented making the window go fullscreen with XRandR and can change the display ...
1
vote
0answers
150 views

Matrix array doesn't seem to get populated [closed]

I'm trying to stream an array of matrices to a vertex shader, but it seems that only the first matrix works. What could be the problem? I suspect that I upload the matrices in a wrong way. C# ...
1
vote
1answer
618 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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votes
1answer
350 views

Using Shader causes triangle to disappear

The following is my rendering code. Private Sub GameRender() GL.Clear(ClearBufferMask.ColorBufferBit + ClearBufferMask.DepthBufferBit) GL.ClearColor(Color.SkyBlue) ...
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votes
1answer
425 views

OS X OpenGL 3.2 Core (Black Screen)

I want to render a Quad via VAO, IBO and VBO but nothing is drawn. I'm using glDrawRangeElements in OS X OpenGL 3.2 Core context. The screen is completely black without any error. GLFW3 is used to ...
1
vote
1answer
243 views

Why does calling GL.Color4 result in a blank screen?

I am learning OpenGL using OpenTK and VB.NET. I made a square with a texture: GL.Begin(BeginMode.Quads) GL.TexCoord2(0.0, 0.0) GL.Vertex3(-1.0, 1.0, 0.0) GL.TexCoord2(1.0, 0.0) ...
3
votes
1answer
764 views

Incorrect GPU skinning

I'm having some problems with implementing skinning and skeletal animation. It seems that the skeleton and the mesh are loaded correctly, but the mesh gets funky when the bone transformations are ...
1
vote
1answer
127 views

Understanding VAOs and adding different arrays to VAOs

I'm really confused on what you do. I can do them, however I got this problem. Say you have several squares, say 1,000 squares. Now I can make a VAO for each 1,000 squares and then do some for loop to ...
3
votes
1answer
312 views

How do I use more than 32 textures in my game?

I'm building a game in OpenGL, relying on shaders as much as possible because python. However, I think I've been working under a misunderstanding of OpenGL since I started. I've abstracted stuff into ...
1
vote
0answers
104 views

Rotate view matrix based on touch coordinates

I'm working on an Android game where I need to rotate the camera around the origin based on the user dragging their finger. My view matrix has initial position of sitting on the negative z and facing ...
1
vote
2answers
261 views

LWJGL - If I use VBOs what can I do about separate textures?

So basically this is my problem: I am creating a game that needs a texture for each object. Now I would use a sprite sheet but the textures are different sizes. I am using VBOs and I need to some how ...
0
votes
1answer
201 views

OpenGL assets and new OpenGL context

So I have a bunch of meshes, materials, etc and then all of a sudden the window needs to be torn down and then recreated (such as switching on fullscreen with GLFW) which means I will get a new OpenGL ...
1
vote
2answers
1k 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 ...
3
votes
1answer
130 views

Pyglet: text.Label().draw to FBO?

I just started OpenGL (PyopenGl) & Pyglet 3 weeks ago, and decided to read the Red Book. So sorry if my question shows my lack of comprehension... My question is: Is it possible to display/write ...
8
votes
2answers
1k views

OpenGL get the outline of multiple overlapping objects

I just had an idea for my on-going-game made with opengl in c++: I'd like to have a big outline (5-6 pixel) on multiple overlapping object when the player win something. I thought the best way is to ...
4
votes
1answer
1k views

using heightmap to simulate 3d in an isometric 2d game

I saw a video of an 2.5d engine that used heightmaps to do zbuffering. Is this hard to do? I have more or less no idea of Opengl(lwjgl) and that stuff. I could imagine, that you compare each pixel ...
3
votes
1answer
284 views

Do GLSL 4.x subroutine variables cause any performance overhead?

There's not too much deep information about them on the web. How are they implemented and how they work under the hood? I'd like to know that they cause any performance overhead or not, especially in ...
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votes
3answers
1k views

LWJGL vs Slick2D vs OpenGL. What is the difference?

I was wondering what the difference was between LWJGL, Slick2D, and OpenGL. If I'm not mistaken LWJGL is a library and it has the methods and such, but what are the other two for and how do they use ...
-1
votes
1answer
256 views

Storing texture ID's for fast global retrieval [closed]

Simple question: What is the fastest way to retrieve a texture ID, given an enum value? Say I have 100 textures, what would be the fastest way to get one texture ID? Make a texture manager with a ...
1
vote
1answer
822 views

OpenGL FBO, render off screen and texture

I need to do some offscreen render to use the rendered image in something different from OpenGL context (for instance I need to use the image in a QListWidgetItem inside a Qt application). After ...
1
vote
0answers
2k views

Multiple Render Targets, Multiple Fragment Shaders

I render a normal and a depth image of a scene. Then I want to reuse these two images to do further texture/image processing in a second fragment shader. I use a framebuffer with 3 textures attached ...
2
votes
1answer
379 views

Camera scrolling and game boundaries

I am making a platformer game in JBox2D and LWJGL that has a scrolling camera, but I have hit a wall with the boundaries of the camera. Essentially what I have right now is a Box2D world that is ...
25
votes
6answers
2k views

Is OpenGL appropriate for 2D games?

I have been teaching myself the OpenGL library for a while now, and want to start making a game. However, for an easier introduction, I want to start with something 2D, such as a top down ...
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votes
1answer
1k views

Is SDL a game engine? [closed]

I would like to ask if SDL is considered a game engine, or just a library like Open and Direct3D?
4
votes
1answer
241 views

Upload vertex data for particles

I am kind of beginner with opengl. I am using point sprites (currently without any texturing) for my particles. I seem to fail to get them uploaded to the GPU memory correctly. I have readed lots of ...
3
votes
1answer
92 views

Texturing a quad

Drawing a quad with a texture mapped to it with the fixed OpenGL pipeline is one of the easiest things to do in OpenGL. And for some madmaking, mysterious, dumb reason I can't get it to work. I ...
1
vote
1answer
277 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 ...
2
votes
1answer
684 views

Heightmap and Textures

Im trying to find the "best way" to apply a texture to a heightmap with opengl 3.x. Its really hard to find something on google because tutorials are olds and they're all using different methods, im ...
0
votes
1answer
78 views

Vertex and Fragment Shader worldNormal

How to access/calculate worldNormal in a Vertex and Fragment shader ? Thanks a lot !
3
votes
1answer
235 views

How to do gpu batching?

I need to render two shapes with opengl (let's say a cube and a triangular prism) and one of them has texture and the other one has lightning fx. The thing I want to do is first draw texture and ...
3
votes
1answer
327 views

Odd blending result (semi-transparent 2d quad over 3D scene)

I'm working on a GUI library for my game, and I'm having problems with my blending. I have a 3D scene, which I render with glDrawArrays. In the fragment shader the alpha color is hardcoded 1.0f ...
2
votes
2answers
1k views

LWJGL multiple keyboard/mouse input checks

As in many game libraries such as LWJGL, you can check mouse/keyboard events with Mouse.isButtonDown or Keyboard.IsKeyDown. I want to check for button/key presses, not if it's currently pressed down ...
1
vote
1answer
574 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 ...
5
votes
1answer
11k views

Why is Minecraft's default resolution (seemingly) non-standard?

Background: I'm writing some articles on Minecraft in an attempt to introduce 10-year olds to development through modding. I know very little about the game itself, though :) I'm trying to understand ...
0
votes
1answer
139 views

Per-fragment lighting system behaves like ambient lighting system

This is the relevant section of my fragment shader varying vec3 normal; varying vec3 halfv; ... vec4 color = ambient * gl_LightSource[0].ambient; vec3 n = normalize(normal); float ...
1
vote
1answer
235 views

How to deal with lot of textures in one draw call?

I'am currently developing text rendering & some kind of tile based texturing for simple landscape with textures blending. e.g. something like this but in 3D. In first realization I have been used ...
0
votes
3answers
451 views

Using different shaders on the same model at runtime

I've already asked similar but a bit unclear question here but this time I will be very specific and to the point. Suppose I have an actor which grabs a power up. He starts to glow using bloom shader ...
9
votes
1answer
1k views

Engine Rendering pipeline : Making shaders generic

I am trying to make a 2D game engine using OpenGL ES 2.0 (iOS for now). I've written Application layer in Objective C and a separate self contained RendererGLES20 in C++. No GL specific call is made ...
0
votes
1answer
343 views

GLSL: Strange light reflections

According to this tutorial I'm trying to make a normal mapping using GLSL, but something is wrong and I can't find the solution. The output render is in this image: Image1 in this image is a plane ...
2
votes
1answer
634 views

How to tell what part of a 3D cube was touched

I am writing a rather simple android game and I am implementing Open GL to draw a 3D cube that spins upon the X, Y and Z axis and I need to know where the user has clicked on the texture of the cube. ...