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Questions tagged [opengl-es]

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0
votes
1answer
50 views

Efficiently drawing multiple instances of 3D objects

I was able to write the following working code to draw any number of "sprites" (defined as 2 tringles, 6 vertices) ...
2
votes
1answer
42 views

Alpha component in color buffer affects RGB components?

I'm looking for a way to make my surface semitransparent, and for now i ended up using this configuration: ...
2
votes
0answers
44 views

How to rendered arbitrary rotated text with decent hinting in real time?

I display text using OpenGL which is aligned with (2D) objects that can have any rotation on display, making the text also appear at any angle on display. So far I've used FreeType to render raster ...
3
votes
1answer
79 views

If I have more than enough memory, can it still be beneficial to use compressed textures?

I'm wondering whether some of you would have tested and seen quite a difference in using a compressed texture even when the OpenGL environment does not need saving any memory (i.e. the card has more ...
2
votes
2answers
59 views

How to take consistent screenshots across multiple machines?

I have some OpenGL based software and I would like to set up some automated testing using image comparison, but one problem we always have is that the screenshots we take always have some small ...
2
votes
1answer
54 views

What is wrong with my glDrawElement code

I am reading a model from an obj file and draw it using glDrawElements. For some reasons, only a small part of it is drawn, even though I dont even have back-face culling turned on. ...
1
vote
0answers
69 views

OpenGL ES 3.0 - Uniform Buffer Object non-static indexing

I've encountered a very strange issue while testing UBO on Android device: if I try to index UBO array with non-constant index, the program fails to link with log: ...
1
vote
2answers
116 views

Loading compressed image to GPU and reading back decompressed on CPU

I have some images that I know will be stored with either PVR or ETC compression. I would like to be able to convert these images into uncompressed RGB. However, because of binary size constraints, I ...
4
votes
1answer
121 views

Any way to fake textureLod on GLES2?

I've been having nightmares at work this week trying to get Unity's Standard shader, and my own custom car paint shader modded from it, to look good on Android. The most obvious problem was ...
1
vote
3answers
130 views

Same specular lighting on both tris in a quad (for “low-poly” “flat shading” look)?

Here's an example of the flat shaded squares I want. But my squares are made of two triangles, and I'm getting flat shading of those triangles. In openGLES 3.1 (android), I'm turning off ...
1
vote
1answer
328 views

Blending for Floating Point Texture

I'm confused how does the GL_SRC_ALPHA_SATURATE function effect a 32 bit floating point texture attachment in FBO while blending colors. In the reference the equation is: Here what is the value of kA ...
1
vote
0answers
28 views

Can OpenGL ES 2.0 api calls be integrated with a Direct3D application using ANGLE?

I have an OpenGL ES 2.0 based application and I want to integrate most of its code into an engine that uses Direct3D? Is it possible to integrate code that makes OpenGL ES calls into a DirectX based ...
1
vote
1answer
33 views

iPhone GLU(OpenGL Utility Library)

This link says iPhoneGLU says, this libraray supports below futures. Matrix manipulation Polygon tessellation I would like to know whether I can use this library to draw primitives(lines,points,...
1
vote
0answers
470 views

'glGenVertexArrays’ was not declared in this scope

I wrote an OpenGL program on Windows that I am trying to port to a Raspberry Pi 3 running Raspian OS. When I try to compile, I get the following errors: include/object.h|44|error: ‘...
1
vote
0answers
97 views

Is there a concept for a cross platform GUI?

I have developed a C++ core application, which needs a relatively simple GUI, like a mind map. Now I wish to find a multipurpose solution for the visualization. So far my effort: three.js (webgl) in ...
1
vote
1answer
2k views

OpenGL ES 3 - Uniform buffer object with float array

I'm trying to load an array of float to a fragment shader using a uniform buffer object, but it doesn't work. In the fragment shader I declared the following uniform block: ...
6
votes
1answer
971 views

Why can't I utilize multiple CPU cores with OpenGL like Vulkan?

Can I pass the data to the GPU through multiple cores with OpenGL?
5
votes
1answer
167 views

Pixel density / color channel depth ratio for dithered gradients

Dithering increases percieved color depth by adding a "noise" to an image on transform from high color depth (e.g. 32-bit floating point) to lower color depth (e.g. 8-bit integer). A prerequisite is ...
4
votes
1answer
177 views

OpenGL ES Frag Shader - Branching

Working on optimizing a fragment shader which is slowing down my OpenGL ES 2.0 shader based game. This is used with a shadow buffer to determine if the fragment/pixel is inside a shadow volume. The ...
15
votes
3answers
6k views

Physically based shading - ambient/indirect lighting

I implemented a physically based path tracer after studying PBRT by M. Pharr and G. Humphreys. Now I'm trying to apply physically based rendering to real time graphics using OpenGL ES (in an iPhone ...
5
votes
0answers
361 views

OpenGL ES vertex/fragment shaders - Blinn phong

I'm developing a simple educational project to study OpenGL ES. I'm try to render some simple OBJ models using Blinn-Phong. The first version of the of my implementation calculate all the lighting ...
5
votes
1answer
465 views

Generation of lower resolution textures

So I have a game and I am trying to fake glow inside of it by using the hardwares capability to downsize textures causing them to blur. The texture I wish to do this with is in a render buffer that ...
4
votes
1answer
164 views

What is causing this odd scaling behavior?

OK so I have a simple setup going on. Basically I am just drawing some textures and shapes. However sizing is going weird... let me show you how any maybe you can diagnose. Basically everything is ...
4
votes
1answer
59 views

Interlacing vertex buffer data with extra efficiency

I am making a 2d game in opengl es 2.0 Inside are tons of rectangles defined by 4 points and one 4 component color. I am using vertex buffer objects, and I have heard that it is efficent to ...
4
votes
0answers
112 views

Strange behaviour of glDisableVertexAttribArray() on devices

In my graphics engine, based on OpenGL ES 2.0 I am using standardized name for shader attributes like it is done in libGDX (such as a_position, a_normal, etc.). When 'activating' my vertex buffer for ...
6
votes
1answer
454 views

SSAO artefacts on iPhone (OpenGL ES)

I've never written shaders before, and now I'm trying to implement SSAO with SceneKit on OS X and iOS. I'm trying different SSAO shaders that I find, e.g. from Three.js, this one, and this one. On OS ...
7
votes
1answer
492 views

How to implement a realtime 2D light renderer with fog/colored light on the GPU?

Since long ago I wanted to implement a 2D lightning algorithm based on an idea I saw on YouTube. The video is realtime, but it runs on the CPU and the resolution is pretty low. I'm curious if anyone ...
5
votes
2answers
2k views

How to reduce the number of draw calls when rendering one object multiple times?

Especially when rendering particle effects, the same object needs to be rendered several times with slightly modified properties. But these changes are often limited to properties like pose or ...