Sign in to follow this  

OpenGL Android + OpenGL ES...double buffered? threaded? gameloop?

This topic is 2082 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

3 questions...but first, here's my setup

My activity class:
[CODE]
...useless stuff...
import android.opengl.GLSurfaceView;

public class MyApp extends Activity
{
private GLSurfaceView mSurfaceView;
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE); //fullscreen
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
glSurfaceView = new GLSurfaceView(this);
glSurfaceView.setRenderer(new MyRenderer());
setContentView(glSurfaceView);
}
}
[/CODE]

My Renderer class
[CODE]
...unimportant stuff...
import android.opengl.GLSurfaceView.Renderer;
public class MyRenderer implements Renderer
{
@Override
public void onDrawFrame(GL10 gl)
{
...iterate over draw objects and call .draw() on them...
}
}
...more unimportant stuff...
[/CODE]

1) Is OpenGL ES double buffered by default?
Right now, I've created a Renderer class that extends GLSurfaceView.Renderer. From that, I've got an override for onDrawFrame...like you can see above. Is this already double buffered? I've done a little bit of OpenGL coding for PC and I remember having to specifically tell it to swap buffers...

2) Given my current setup, is the renderer already on its own thread? Is that something handled by OpenGL ES (or the GLViewPort class)?

3) Right now I'm doing everything inside of the onDrawScene(GL10 gl) function. Is there a better way of creating a game loop? Seems like (assuming rendering is currently on its own thread), onDrawScene should just iterate of my drawable objects and draw them, but I should probably have a loop in another thread somewhere polling input, updating drawable object positions, etc. Any thoughts?

Thanks, in advance, for the help!

[Edit: spelling error] Edited by Holland

Share this post


Link to post
Share on other sites
AFAIK Android uses EGL. So it all depends on what the Java crap is doing under the hood to initialize your EGL content.

You could either dig into the Android codebase (ugly, full of hacks) or just ditch Java and take control by doing all the initialization with your own code in C++.

Share this post


Link to post
Share on other sites
1) OpenGL ES isn't double buffered by default, but GLSurfaceView uses double buffering in your configutration (eglSwapBuffer is called automatically). you can change this behaviour if you call setRenderMode(RENDERMODE_WHEN_DIRTY), now you can force swapbuffer yourself by calling requestRender() (Look at GLSurfaceView on the reference page)

Tripple Buffering is also possible, look for the video about OpenGL developing from the last google IO. The guy explains how to use triple buffering for benchmarking purposes (with double buffering most devices have a fixed output of 30 / 60 fps)

2) The renderer is indeed on its own thread, GLSurfaceView starts the Thread after setRenderer() get's called. I've rewritten this class for Wallpaper-rendering with OpenGL ES 2.0 and took a deeper look. GLSurfaceView does all the EGL things with the more complicated android stuff for your, handling the RenderThread, Managnig the EGLContext (important because of the different behaviours on different devices, when other activities need a lock on the EGLContext - not trivial to manage this on your own)

3) I've choosen the way to build up two extra Threads for my current developments (one for logic, one for animations, several others are launched by android like SensorThread for polling accelerometer). In general I could say these things:
- don't do heavy work on androids UIThread, which isn't the case if you do it in onDrawFram() because now its done by the renderThread
- if you do heavy work like IO-operations use a ASyncTask
- its hard to implement extra threads in the java manner (new Thread and calling run() ) because you have to take care of the whole synchronizing and more care on
bringing your Threads to idle-state if your activity is paused (or you app is a battery drainer). This isn't the preferable way as long as you haven't performance problems while using the render-thread

Avoid using native code, except you have to (ready c / c++ implemantations) - the dalvik vm is really fast, especially since it uses a JIT-Compiler (since API-Level 8 I think).
You still have to call your c/c++ written wrapper methods through JAVA (with JNI / NDK), nothing else the Android-API is doing So you don't have a performance increase, except your logic is handled here and you make use of special ARM CPU features like the NEON-platform or similar things

Look a christmas 3D on android market, if your device can handle it you'll see 2 things
first: all resource are loaded in the render-thread, not with a async task (very long load time, user can't see anything)
second: camera handling, matrix operations, particle calculation are also handled in the render task, but with less performance penalty than thread handling -->
the need of an extra thread depends on what logic work you have to do

Share this post


Link to post
Share on other sites
Sign in to follow this  

  • Similar Content

    • By khawk
      We've just released all of the source code for the NeHe OpenGL lessons on our Github page at https://github.com/gamedev-net/nehe-opengl. code - 43 total platforms, configurations, and languages are included.
      Now operated by GameDev.net, NeHe is located at http://nehe.gamedev.net where it has been a valuable resource for developers wanting to learn OpenGL and graphics programming.

      View full story
    • By TheChubu
      The Khronos™ Group, an open consortium of leading hardware and software companies, announces from the SIGGRAPH 2017 Conference the immediate public availability of the OpenGL® 4.6 specification. OpenGL 4.6 integrates the functionality of numerous ARB and EXT extensions created by Khronos members AMD, Intel, and NVIDIA into core, including the capability to ingest SPIR-V™ shaders.
      SPIR-V is a Khronos-defined standard intermediate language for parallel compute and graphics, which enables content creators to simplify their shader authoring and management pipelines while providing significant source shading language flexibility. OpenGL 4.6 adds support for ingesting SPIR-V shaders to the core specification, guaranteeing that SPIR-V shaders will be widely supported by OpenGL implementations.
      OpenGL 4.6 adds the functionality of these ARB extensions to OpenGL’s core specification:
      GL_ARB_gl_spirv and GL_ARB_spirv_extensions to standardize SPIR-V support for OpenGL GL_ARB_indirect_parameters and GL_ARB_shader_draw_parameters for reducing the CPU overhead associated with rendering batches of geometry GL_ARB_pipeline_statistics_query and GL_ARB_transform_feedback_overflow_querystandardize OpenGL support for features available in Direct3D GL_ARB_texture_filter_anisotropic (based on GL_EXT_texture_filter_anisotropic) brings previously IP encumbered functionality into OpenGL to improve the visual quality of textured scenes GL_ARB_polygon_offset_clamp (based on GL_EXT_polygon_offset_clamp) suppresses a common visual artifact known as a “light leak” associated with rendering shadows GL_ARB_shader_atomic_counter_ops and GL_ARB_shader_group_vote add shader intrinsics supported by all desktop vendors to improve functionality and performance GL_KHR_no_error reduces driver overhead by allowing the application to indicate that it expects error-free operation so errors need not be generated In addition to the above features being added to OpenGL 4.6, the following are being released as extensions:
      GL_KHR_parallel_shader_compile allows applications to launch multiple shader compile threads to improve shader compile throughput WGL_ARB_create_context_no_error and GXL_ARB_create_context_no_error allow no error contexts to be created with WGL or GLX that support the GL_KHR_no_error extension “I’m proud to announce OpenGL 4.6 as the most feature-rich version of OpenGL yet. We've brought together the most popular, widely-supported extensions into a new core specification to give OpenGL developers and end users an improved baseline feature set. This includes resolving previous intellectual property roadblocks to bringing anisotropic texture filtering and polygon offset clamping into the core specification to enable widespread implementation and usage,” said Piers Daniell, chair of the OpenGL Working Group at Khronos. “The OpenGL working group will continue to respond to market needs and work with GPU vendors to ensure OpenGL remains a viable and evolving graphics API for all its customers and users across many vital industries.“
      The OpenGL 4.6 specification can be found at https://khronos.org/registry/OpenGL/index_gl.php. The GLSL to SPIR-V compiler glslang has been updated with GLSL 4.60 support, and can be found at https://github.com/KhronosGroup/glslang.
      Sophisticated graphics applications will also benefit from a set of newly released extensions for both OpenGL and OpenGL ES to enable interoperability with Vulkan and Direct3D. These extensions are named:
      GL_EXT_memory_object GL_EXT_memory_object_fd GL_EXT_memory_object_win32 GL_EXT_semaphore GL_EXT_semaphore_fd GL_EXT_semaphore_win32 GL_EXT_win32_keyed_mutex They can be found at: https://khronos.org/registry/OpenGL/index_gl.php
      Industry Support for OpenGL 4.6
      “With OpenGL 4.6 our customers have an improved set of core features available on our full range of OpenGL 4.x capable GPUs. These features provide improved rendering quality, performance and functionality. As the graphics industry’s most popular API, we fully support OpenGL and will continue to work closely with the Khronos Group on the development of new OpenGL specifications and extensions for our customers. NVIDIA has released beta OpenGL 4.6 drivers today at https://developer.nvidia.com/opengl-driver so developers can use these new features right away,” said Bob Pette, vice president, Professional Graphics at NVIDIA.
      "OpenGL 4.6 will be the first OpenGL release where conformant open source implementations based on the Mesa project will be deliverable in a reasonable timeframe after release. The open sourcing of the OpenGL conformance test suite and ongoing work between Khronos and X.org will also allow for non-vendor led open source implementations to achieve conformance in the near future," said David Airlie, senior principal engineer at Red Hat, and developer on Mesa/X.org projects.

      View full story
    • By _OskaR
      Hi,
      I have an OpenGL application but without possibility to wite own shaders.
      I need to perform small VS modification - is possible to do it in an alternative way? Do we have apps or driver modifictions which will catch the shader sent to GPU and override it?
    • By xhcao
      Does sync be needed to read texture content after access texture image in compute shader?
      My simple code is as below,
      glUseProgram(program.get());
      glBindImageTexture(0, texture[0], 0, GL_FALSE, 3, GL_READ_ONLY, GL_R32UI);
      glBindImageTexture(1, texture[1], 0, GL_FALSE, 4, GL_WRITE_ONLY, GL_R32UI);
      glDispatchCompute(1, 1, 1);
      // Does sync be needed here?
      glUseProgram(0);
      glBindFramebuffer(GL_READ_FRAMEBUFFER, framebuffer);
      glFramebufferTexture2D(GL_READ_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
                                     GL_TEXTURE_CUBE_MAP_POSITIVE_X + face, texture[1], 0);
      glReadPixels(0, 0, kWidth, kHeight, GL_RED_INTEGER, GL_UNSIGNED_INT, outputValues);
       
      Compute shader is very simple, imageLoad content from texture[0], and imageStore content to texture[1]. Does need to sync after dispatchCompute?
    • By Jonathan2006
      My question: is it possible to transform multiple angular velocities so that they can be reinserted as one? My research is below:
      // This works quat quaternion1 = GEQuaternionFromAngleRadians(angleRadiansVector1); quat quaternion2 = GEMultiplyQuaternions(quaternion1, GEQuaternionFromAngleRadians(angleRadiansVector2)); quat quaternion3 = GEMultiplyQuaternions(quaternion2, GEQuaternionFromAngleRadians(angleRadiansVector3)); glMultMatrixf(GEMat4FromQuaternion(quaternion3).array); // The first two work fine but not the third. Why? quat quaternion1 = GEQuaternionFromAngleRadians(angleRadiansVector1); vec3 vector1 = GETransformQuaternionAndVector(quaternion1, angularVelocity1); quat quaternion2 = GEQuaternionFromAngleRadians(angleRadiansVector2); vec3 vector2 = GETransformQuaternionAndVector(quaternion2, angularVelocity2); // This doesn't work //quat quaternion3 = GEQuaternionFromAngleRadians(angleRadiansVector3); //vec3 vector3 = GETransformQuaternionAndVector(quaternion3, angularVelocity3); vec3 angleVelocity = GEAddVectors(vector1, vector2); // Does not work: vec3 angleVelocity = GEAddVectors(vector1, GEAddVectors(vector2, vector3)); static vec3 angleRadiansVector; vec3 angularAcceleration = GESetVector(0.0, 0.0, 0.0); // Sending it through one angular velocity later in my motion engine angleVelocity = GEAddVectors(angleVelocity, GEMultiplyVectorAndScalar(angularAcceleration, timeStep)); angleRadiansVector = GEAddVectors(angleRadiansVector, GEMultiplyVectorAndScalar(angleVelocity, timeStep)); glMultMatrixf(GEMat4FromEulerAngle(angleRadiansVector).array); Also how do I combine multiple angularAcceleration variables? Is there an easier way to transform the angular values?
  • Popular Now