Questions tagged [opengl-es]

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Artifacts Multi UV Branching on GPU

Problem I'm currently working on multi UV support for glTF-models, and after getting a first version up and running (checking against glTF's multi-uv-test) I checked if the other models are still ...
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Achieving bokeh blur with custom shapes

I have a 2D texture, without any depth maps, which I'd like to blur to achieve a bokeh effect. The catch, however, is that I want the effect to be custom bitmaps/shapes (e.g. a heart). Here's a part ...
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Tiling in GLSL creates unwanted seams

I'm writing a shader that creates a grid with coloured tiles. The color is derived from a pixel at that location on a texture. But around the tiles I get these unwanted seams. I can't seem to figure ...
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If a GPU supports OpenGL ES 3.2, does it also support OpenGl 3.0?

At the moment I am looking for a tablet to use the bike simulator app "BKOOL". The Samsung Galaxy Tab S6 Lite is my current favorite and it meets almost all app requirements (https://www....
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glTexImage2d from bytebuffer

I want to create a single-channel 2d texture with bytebuffer which contain each float for each pixel (let say it is an alpha value) to use further in shader Btw, I've tried this ...
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Shadow volume/stencil shadow penumbra rendering

While I am not looking for a method to render soft stencil shadows, I am trying to achieve hard shadow rendering that is extended to include the penumbra regions of a shadow for omni-directional ...
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1 answer
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How to pass only the needed portion of the data calculated in a fragment shader to another fragment shader?

I have an image and I want to draw an arbitrary number of objects on that image. The center coordinates of those objects are calculated inside a fragment shader after series of image processing ...
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1 vote
1 answer
417 views

When unsetting a VAO, should you also unbind the associated VBOs?

I'm working with a js/wasm/c++ program that uses object oriented programming when updating the OpenGL state. There are corresponding c++ classes for VBOs (vertex buffer) and VAOs (vertex array). ...
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Best practice for managing many shaders and merging multiple shaders into one?

I have managed to greatly minimize draw calls on my recent project, but as I'm adding more shaders, I see that I have to switch more times and that is causing a lot of draw calls. What is the best ...
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4 votes
1 answer
397 views

Double buffering always necessary?

Question from the graphics newbie: What I know by now is that "usually" double buffering is used: You calculate the content of frame x+1 while frame x is shown on the screen, if you want to achieve ...
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How combine multiple projections into a single pass?

We have a projector type display used in an automotive application, where a projector displays an application on the windshield. Because the projector would normally warp a flat image, we have to ...
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Are there any reasons to use power of two textures with modern mobile platforms?

Are there any reasons to use power of two textures (like 128x128 sized) if one targets modern mobile platforms (with OpenGL ES 3.0, Metal and/or Vulkan)? With iOS the PVRTC only supports power of two ...
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1 answer
954 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) ...
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1 answer
185 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: ...
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2 votes
0 answers
296 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 ...
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3 votes
1 answer
203 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 ...
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2 answers
79 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 ...
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1 answer
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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. ...
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2 answers
527 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 ...
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3 votes
1 answer
522 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 ...
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1 vote
3 answers
321 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 ...
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2 votes
1 answer
723 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 ...
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1 answer
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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,...
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101 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 ...
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1 vote
1 answer
5k 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: ...
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7 votes
1 answer
2k 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?
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4 votes
1 answer
209 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 ...
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3 votes
1 answer
245 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 ...
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18 votes
3 answers
8k 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 ...
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4 votes
0 answers
600 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 ...
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6 votes
1 answer
1k 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 ...
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3 votes
1 answer
277 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 ...
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2 votes
1 answer
95 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 ...
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3 votes
0 answers
168 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 ...
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6 votes
1 answer
585 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 ...
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7 votes
1 answer
758 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 ...
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5 votes
2 answers
3k 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 ...
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