• Advertisement
Sign in to follow this  

OpenGL Switching PresentInterval after window creation

This topic is 1977 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

Is there some way to switch the present interval dynamically after the window has already been created? I cannot find a way to do that in DirectX9. I can only find how to set it at startup. I know this can be done in OpenGL on Windows, and even in DirectX9 on the Xbox 360. So is there something similar in DirectX9 on PC?

Searching the forum, I found [url="http://www.gamedev.net/topic/424071-mdx-turning-vsync-onoff-without-recreating-swap-chain/"]this old topic[/url], but that suggests I need to reset things to switch VSync. Doing this takes some time, is that correct? Or can that be done at any time in between two frames without causing a framedrop because of the reset?

I know that quite a few games these days have VSync on by default and then dynamically shortly turn if off if the framerate drops too far. When the framerate is back to normal, vsync is then turned on again. How is this done on PC in DirectX9? Or is this only done on consoles?

Share this post


Link to post
Share on other sites
Advertisement
To change VSYNC in DX9 you need to reset the device, which is really slow since you have to release all of your non-managed resources. So you can't change it frame-to-frame to get the "soft VSYNC" effect that you're referring to. In DX10/DX11 the sync interval is a parameter that you pass to Present, so it is possible to change it each frame. However even with that it's still difficult do a soft VSYNC, since you don't have the same amount of low-level timing info and control that you do on consoles. I'm not sure if any PC games have actually shipped with it, but if they did they were surely using DX10 or DX11. (The one notable exception is RAGE, which had Nvidia add a soft VSYNC option into the driver for them). Edited by MJP

Share this post


Link to post
Share on other sites
On Vista and Win7 D3D9Ex has a WaitForVBlank method, which I guess does the same as the DXGI version, though I haven't tried it.
You could also create a DirectDraw device that you use only for VSync. Check out WaitForVerticalBlank, [url="http://msdn.microsoft.com/en-us/library/aa911354.aspx"]http://msdn.microsof...y/aa911354.aspx[/url] or GetVerticalBlankStatus. Edited by Erik Rufelt

Share this post


Link to post
Share on other sites
Okay, sounds like my best option then is to just not support dynamic vsync switching in my engine and move the vsync option from the in-game settings menu to the pre-game launcher.

Kind of funny how some features are impossible in one API, and no problem in another. Same OS, same hardware, but DirectX 9 can't do it and OpenGL can. Guess DX10/11 do have some useful improvements after all. [img]http://public.gamedev.net//public/style_emoticons/default/wink.png[/img]

Thanks for the help, folks! Edited by Oogst

Share this post


Link to post
Share on other sites
[quote name='MJP' timestamp='1345312105' post='4970875']
However even with that it's still difficult do a soft VSYNC, since you don't have the same amount of low-level timing info and control that you do on consoles.
[/quote]Does DX11 have a GPU timestamp read-back API, and a requirement for GPUs to support it? DX9 is lacking this, and GL has it via an extension (not sure which GPUs do and don't support the extension though).
Being able to stamp your frames to get a value on GPU processing time would be a great base-level API requirement ([i]like on consoles[/i]). Even if read-back is delayed, you can use a rolling average to get yourself out of trouble a few frames after vsync starts being consistently harmful.

Share this post


Link to post
Share on other sites
[quote name='Hodgman' timestamp='1345447620' post='4971365']Does DX11 have a GPU timestamp read-back API, and a requirement for GPUs to support it? DX9 is lacking this, and GL has it via an extension (not sure which GPUs do and don't support the extension though).
Being able to stamp your frames to get a value on GPU processing time would be a great base-level API requirement ([i]like on consoles[/i]). Even if read-back is delayed, you can use a rolling average to get yourself out of trouble a few frames after vsync starts being consistently harmful.
[/quote]
Doesn't DirectX have some equivalent of OpenGL's fences? Fences are not exactly what you describe, but they do give some nice information on where the videocard is at the moment. Edited by Oogst

Share this post


Link to post
Share on other sites
[quote name='MJP' timestamp='1345449778' post='4971374']
There are timestamp queries, which are actually available in DX9 as well.
[/quote]You've just blown my mind!
I swear that last time I looked at the local version of [url="http://msdn.microsoft.com/en-us/library/windows/desktop/bb147308(v=vs.85).aspx"]this page[/url] (inside the DirectX SDK's installed documentation), there was no timestamp query.
I was still under the impression that the only method of timing GPU usage under DX9 was the non-real-time, CPU-blocking, flush & finish method [url="http://msdn.microsoft.com/en-us/library/windows/desktop/bb172234(v=vs.85).aspx"]described here[/url].

On consoles, I basically use a ring-buffer of time-stamp queries to detect bad performance; the major check is using the deltas to calculate a rolling average of GPU-frame-time to see if there's consistently bad GPU performance. It seems I can implement this on DX9 as well?

Share this post


Link to post
Share on other sites
[quote name='Hodgman' timestamp='1345451449' post='4971381']
[quote name='MJP' timestamp='1345449778' post='4971374']
There are timestamp queries, which are actually available in DX9 as well.
[/quote]You've just blown my mind!
I swear that last time I looked at the local version of [url="http://msdn.microsoft.com/en-us/library/windows/desktop/bb147308(v=vs.85).aspx"]this page[/url] (inside the DirectX SDK's installed documentation), there was no timestamp query.
I was still under the impression that the only method of timing GPU usage under DX9 was the non-real-time, CPU-blocking, flush & finish method [url="http://msdn.microsoft.com/en-us/library/windows/desktop/bb172234(v=vs.85).aspx"]described here[/url].

On consoles, I basically use a ring-buffer of time-stamp queries to detect bad performance; the major check is using the deltas to calculate a rolling average of GPU-frame-time to see if there's consistently bad GPU performance. It seems I can implement this on DX9 as well?
[/quote]

Yeah I had thought they were new for DX10, but someone else pointed out to me that DX9 has them as well. In my experience the query works pretty much the way you'd expect. Which of course means it has all of the usual latency problems with queries, as well as the "just what exactly am I measuring?" problem you have with reading GPU timestamps. Edited by MJP

Share this post


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

  • Advertisement
  • Advertisement
  • Popular Now

  • Advertisement
  • Similar Content

    • By Balma Alparisi
      i got error 1282 in my code.
      sf::ContextSettings settings; settings.majorVersion = 4; settings.minorVersion = 5; settings.attributeFlags = settings.Core; sf::Window window; window.create(sf::VideoMode(1600, 900), "Texture Unit Rectangle", sf::Style::Close, settings); window.setActive(true); window.setVerticalSyncEnabled(true); glewInit(); GLuint shaderProgram = createShaderProgram("FX/Rectangle.vss", "FX/Rectangle.fss"); float vertex[] = { -0.5f,0.5f,0.0f, 0.0f,0.0f, -0.5f,-0.5f,0.0f, 0.0f,1.0f, 0.5f,0.5f,0.0f, 1.0f,0.0f, 0.5,-0.5f,0.0f, 1.0f,1.0f, }; GLuint indices[] = { 0,1,2, 1,2,3, }; GLuint vao; glGenVertexArrays(1, &vao); glBindVertexArray(vao); GLuint vbo; glGenBuffers(1, &vbo); glBindBuffer(GL_ARRAY_BUFFER, vbo); glBufferData(GL_ARRAY_BUFFER, sizeof(vertex), vertex, GL_STATIC_DRAW); GLuint ebo; glGenBuffers(1, &ebo); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo); glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices,GL_STATIC_DRAW); glVertexAttribPointer(0, 3, GL_FLOAT, false, sizeof(float) * 5, (void*)0); glEnableVertexAttribArray(0); glVertexAttribPointer(1, 2, GL_FLOAT, false, sizeof(float) * 5, (void*)(sizeof(float) * 3)); glEnableVertexAttribArray(1); GLuint texture[2]; glGenTextures(2, texture); glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, texture[0]); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); sf::Image* imageOne = new sf::Image; bool isImageOneLoaded = imageOne->loadFromFile("Texture/container.jpg"); if (isImageOneLoaded) { glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, imageOne->getSize().x, imageOne->getSize().y, 0, GL_RGBA, GL_UNSIGNED_BYTE, imageOne->getPixelsPtr()); glGenerateMipmap(GL_TEXTURE_2D); } delete imageOne; glActiveTexture(GL_TEXTURE1); glBindTexture(GL_TEXTURE_2D, texture[1]); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); sf::Image* imageTwo = new sf::Image; bool isImageTwoLoaded = imageTwo->loadFromFile("Texture/awesomeface.png"); if (isImageTwoLoaded) { glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, imageTwo->getSize().x, imageTwo->getSize().y, 0, GL_RGBA, GL_UNSIGNED_BYTE, imageTwo->getPixelsPtr()); glGenerateMipmap(GL_TEXTURE_2D); } delete imageTwo; glUniform1i(glGetUniformLocation(shaderProgram, "inTextureOne"), 0); glUniform1i(glGetUniformLocation(shaderProgram, "inTextureTwo"), 1); GLenum error = glGetError(); std::cout << error << std::endl; sf::Event event; bool isRunning = true; while (isRunning) { while (window.pollEvent(event)) { if (event.type == event.Closed) { isRunning = false; } } glClear(GL_COLOR_BUFFER_BIT); if (isImageOneLoaded && isImageTwoLoaded) { glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, texture[0]); glActiveTexture(GL_TEXTURE1); glBindTexture(GL_TEXTURE_2D, texture[1]); glUseProgram(shaderProgram); } glBindVertexArray(vao); glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, nullptr); glBindVertexArray(0); window.display(); } glDeleteVertexArrays(1, &vao); glDeleteBuffers(1, &vbo); glDeleteBuffers(1, &ebo); glDeleteProgram(shaderProgram); glDeleteTextures(2,texture); return 0; } and this is the vertex shader
      #version 450 core layout(location=0) in vec3 inPos; layout(location=1) in vec2 inTexCoord; out vec2 TexCoord; void main() { gl_Position=vec4(inPos,1.0); TexCoord=inTexCoord; } and the fragment shader
      #version 450 core in vec2 TexCoord; uniform sampler2D inTextureOne; uniform sampler2D inTextureTwo; out vec4 FragmentColor; void main() { FragmentColor=mix(texture(inTextureOne,TexCoord),texture(inTextureTwo,TexCoord),0.2); } I was expecting awesomeface.png on top of container.jpg

    • 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?
  • Advertisement