Tagged Questions
1
vote
2answers
84 views
Calling glGetError() in release builds?
Currently, I'm calling glGetError() after each OpenGL function call in order to be able to detect and report bugs.
I've been reading that glGetError() calls should be reduced to once per frame in ...
1
vote
1answer
167 views
Selecting and moving object in OpenGL Gameplay3D Engine
I'm using Gameplay3d as a game engine to develop a simple board game. PEG Solitaire
I've come to the part where I've created a 2D grid for all the movable object, empty locations and also where it's ...
2
votes
0answers
92 views
Displacement Mapping opengl-es
I need to do an application similar to this Morfo. And I posted a question here where the answer states the solution is "Displacement Mapping" . And I googled this to do it in opengles. I couldnt get ...
0
votes
1answer
65 views
Interleaved formats for meshes confusion
So 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 ...
7
votes
1answer
339 views
How wise is this multithreading architecture?
I'm rewriting a game engine I wrote in an attempt to parallelize as much as possible. I'm considering making properties which may be accessed from multiple threads all use accessors which use boost ...
3
votes
0answers
63 views
Rotate an image and get back to its original position - opengles glkit
I need to rotate an image in opengles GLkit and get it back to its original position in GLkit.
rotation += 5;
_modelViewMatrix = GLKMatrix4Rotate( _modelViewMatrix, GLKMathDegreesToRadians(5), 1, 0, ...
1
vote
1answer
174 views
OpenGL ES screen to world coordinate
I am currently attempting to convert my screen coordinates to world coordinates, to be able to interact with objects. I am using glm and unProject to try and achieve this, so far this is my code:
...
0
votes
0answers
45 views
iOS billboard rendering performance
What is the fastest way to render semi-transparent billboards (for a particle system) on iOS? I'm currently using GLES1, but if required for performance I can switch to GLES2.
Does sorting the quads ...
1
vote
2answers
96 views
How to get a texture from current point of view in OpenGL 2.0 ES?
Probably the title is confusing, but I didn't know how to ask better, sorry about that. What I would like to do is get a bitmap texture that represents exactly what's rendered at one point in time and ...
0
votes
0answers
75 views
Starting OpenGL ES 2 [closed]
Really, I'm a bit confused now.
I want to learn OpenGL ES 2, and eventually make games for Android and iPhone.
Thing is, I don't really have any of these devices, so I need solution for emulating ...
3
votes
1answer
147 views
Fill texture with white color
How to paint texture with white color? Example what I mean:
SpriteBatch.setColor changes tint only.
1
vote
1answer
236 views
Apply portion of texture atlas
I'm trying to write a shader that only maps a portion of a large texture to my sprite and I'm getting a strange behaviour with my current code.
This is what I have right now:
Texture atlas ...
2
votes
0answers
367 views
exporting bind and keyframe bone poses from blender to use in OpenGL
EDIT: I decided to reformulate the question in much simpler terms to see if someone can give me a hand with this.
Basically, I'm exporting meshes, skeletons and actions from blender into an engine ...
2
votes
2answers
321 views
The purpose of using invert and transpose
In openGl ES and the World of 3D - why use the invers matrix?
The thing is that I dont have any intuition to, why it is used, therefore please correct me:
As fare as I understand, it is used in ...
2
votes
1answer
389 views
Bad FPS for smaller size (OpenGL ES with SDL)
If you saw my other question, well, there is still a little problem:
Click here to watch on youtube
Basically, the frame rate is very bad on the actual device, where for some reason the animation is ...
0
votes
1answer
161 views
OpenGLES GLSL Shader attributes always bound to 0
So I have a very simple vertex shader as follows
#version 120
attribute vec3 position;
attribute vec3 inColor;
uniform mat4 mvp;
varying vec3 fragColor;
void main(void){
fragColor = inColor;
...
4
votes
3answers
2k views
What is the purpose of glScissor?
I know that it is more efficient than stencil test, but am I right assuming that the same functionality could be achieved using projection transformations with viewport?
0
votes
1answer
125 views
Artifacts when draw particles with some alpha
I want to draw in my game some particles. But when I draw one particle above another particle, alpha channel from this above "clear" previous drawed particle.
I set in OpenGL blend in this way:
...
1
vote
3answers
123 views
How to handle wildly varying rendering hardware / getting baseline
I've recently started with mobile programming (cross-platform, also with desktop) and am encountering wildly differing hardware performance, in particular with OpenGL and the GPU. I know I'll ...
12
votes
1answer
736 views
Should I distribute shaders in a compiled form or in plain text?
Having an application that uses shaders that have been wrote in GLSL, what is the best strategy for the distribution in the real world and for the desktop and mobile?
I'm aiming to distribute this in ...
1
vote
1answer
145 views
if a desktop machine supports OpenGL 3.0+ I can assume that it supports OpenGL ES 2.0 too?
This isn't clear for me, if i use the drivers from the GPU manufacturer and they support OpenGL 3.0 and/or above, i can always make an OpenGL ES 2.0 application work?
1
vote
0answers
163 views
Getting contour without the background
I have a texture and vertex which are needed to create a set of closed polygons. For this purpose I use these functions:
Code for create texture:
CCSprite* spr = ...
1
vote
3answers
1k views
How do I render .dae models?
I'm building a game for iOS. I'm quite new to OpenGL but what I want is to take a 3D model I have made in Google SketchUp and use it in my 3d game. The problem is I don't know how to proceed. I have ...
0
votes
2answers
372 views
Help with Meshes, and Shading
In a game I'm making in LibGdx, I wish to incorporate a ripple effect. I'm confused as to how I get access to the individual pixels on the screen, or any way to influence them (apart from what I can ...
3
votes
2answers
3k views
Creating an OpenGL FPS camera: I have the position and orientation vectors, now what?
I have been struggling to create a first person camera in OpenGL ES 2.0 without using gluLookAt(). I grab the camera's orientation vectors (the way it's looking) from the current modelview matrix, and ...
0
votes
0answers
228 views
Camera rotation flicker in OpenGL ES 2.0
I implemented an orbit camera in my own OpenGL ES 2.0 application.
I was getting extensive amount of flicker while rotating the camera using the mouse.
When I added the line eglSwapInterval( ..., ...
3
votes
4answers
2k views
Geometry instancing in OpenGL ES 2.0
I am planning to do geometry instancing in OpenGL ES 2.0
Basically I plan to render the same geometry(a chair) maybe 1000 times in my scene.
What is the best way to do this in OpenGL ES 2.0?
I am ...
1
vote
1answer
248 views
Adjust sprite bounds of the visible part of texture
Is there any way to adjust the boundaries of the visible part of the sprite? To make it easier to understand: I have a texture, such as shown at figure 1. Then I break it into pieces and fill the ...
0
votes
1answer
270 views
Straightforward guidelines for converting OpenGL to OpenGL ES?
Is there a straightforward list of finite steps that I need to follow to convert an OpenGL program into an OpenGL ES that's used on the iPhone and iPad? I'd be using GLKit.
I've seen some similar API ...
4
votes
3answers
6k views
glTranslate, how exactly does it work?
I have some trouble understanding how does glTranslate work.
At first I thought it would just simply add values to axis to do the transformation.
However then I have created two objects that would ...
0
votes
1answer
1k views
Texture displays on Android emulator but not on device
I have written a simple UI which takes an image (256x256) and maps it to a rectangle. This works perfectly on the emulator however on the phone the texture does not show, I see only a white ...
1
vote
1answer
495 views
How can I add a parallax effect into my side-scrolling game?
How can I add a parallax effect into my side-scrolling game? I read a lot about parallax scrolling so I know what the logic is and what parallax is but I can't create a dynamic parallax effect.
I ...
2
votes
1answer
592 views
OpenGL ES drop shadows for 2D sprites
I've got a an OpenGL scene rendered with a bunch of sprites, and I'd like to automagically add drop shadows to all of them. Here's a picture showing what I mean:
The scene uses orthographic ...
2
votes
0answers
603 views
Can one use OpenGL ES from Google Go?
I've recently used Google's Go language and was impressed by its great support for parallelism. I'd like to try Go for a simple game -- just a test-case -- and I'm wondering if I can use OpenGL ES ...
5
votes
2answers
567 views
Best way to do buttons for an OpenGL ES iPhone game
I'm making a simple 2d game in OpenGL ES and I want to add movement buttons to it. What's the best way of going about this? In previous projects I've simply added UIButtons to the view but I hear ...
2
votes
2answers
2k views
How to use OpenGL's glUseProgram?
While in the rendering loop, is it OK to call glUseProgram? Does it have a big overhead? I'm planing to use a program for each different material in the scene. I'm a real beginner with OpenGL and I'm ...
8
votes
3answers
2k views
How can I bend an object in OpenGL?
Is there a way one could bend an object, like a cylinder or a plane using OpenGL?
I'm an OpenGL beginner (I'm using OpenGL ES 2.0, if that matters, although I suspect, math matters most in this case, ...
3
votes
1answer
1k views
Changing the color of some fragment of a texture using shaders
Declarative programming language QML allows to connect the elements, their properties with universal variables in shader programs description. For these purposes there is such elements as ...
3
votes
2answers
332 views
What is UVIndex and how do I use it on OpenGL?
I am a noob in OpenGL ES 2.0 (for WebGL) and I'm trying to draw a simple model I've made with a 3D tool and exported to .fbx format. I've been able to draw some models that only have: A vertex buffer, ...
1
vote
2answers
308 views
What do I need to know for writing code for both OpenGL and OpenGL ES 2.0
I am developing an engine that uses both OpenGL and OpenGL ES 2.0. I am well seasoned in OpenGL but not ES (although I am aware it is a subset of OpenGL). I could not find a set of differences that I ...
3
votes
1answer
392 views
Unusual Lighting Effects - Random Polygons Coloured
I am working on creating an object loader for use with iOS, I have managed to load the vertices, normals and face data from and OBJ file, and then place this data into arrays for reconstructing the ...
0
votes
0answers
487 views
Projective Transfrom Image Warping on iPhone
I'd like to perform a projective-transformation (a.k.a. perspective-transformation) warp on an image.
Given the 4 2D corners of the source and target quadrangles (from these the 3x3 Homography matrix ...
4
votes
4answers
3k 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 ...
0
votes
2answers
371 views
Linear Interpolation Causing Gimbal Lock?
I have created an object movement path in a 3D authoring application. Then, I exported the path (100 frames) into my custom text file in the form of Euler Angles.
The next point was loading the ...
1
vote
2answers
3k views
OpenGL ES 2.0: Controlling Transparency in Fragment Shader
The following is the OpenGL ES 2.0 simple GLSL Fragment Shader, I use to place textures on polygons, to render 2D sprites.
varying mediump vec2 TextureCoordOut;
uniform sampler2D Sampler;
void ...
0
votes
2answers
1k views
OpenGL ES 2.0: Perspective Projection for 2D Games
Prespective Projection has features that could be very well used even in 2D games. At least two very beneficial characteristics that come to my mind are:
Using Perspective Projection to substitute ...
5
votes
1answer
4k 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 ...
0
votes
2answers
1k views
OpenGL ES 2.0: Calculated Cube Vertex Normals Verification
Could I kindly ask to confirm, that the calculated normals are correct, please? I have calculated them on my own, but my testcube is still strangely lighted within OpenGLES 2.0.
The vertices were ...
1
vote
1answer
1k views
OpenGL ES 2.0: Converting GL_TRIANGLES into GL_TRIANGLE_STRIP
I export my 3D geometry from a 3D authoring application. It is possible to export the vertex coordinates as full triangle arrays.
On ther other hand, triangle strips are more efficient for the ...
1
vote
1answer
3k views
OpenGL ES 2.0: Moving Camera in Orthogonal (2D) Projection
I have quite large 2D game scene. The scene is much larger than the screen of the LCD. Therefore, I have to move the camera (view) in desired directions, to display particular parts of the scene.
...
