Sign in to follow this  

OpenGL OpenGL 1.1 to OpenGL 3 wrapper

This topic is 1736 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

Hi. I came across TWL (Themable Widget Library, http://twl.l33tlabs.org/) when looking for a GUI library for Java + OpenGL (LWJGL).

 

It looks pretty nice and there is an editor and all. The drawback is that is coded against OpenGL 1.1 spec and I'm using OpenGL 3.3 core.

 

So I looked at the sources to see if I could code a wrapper to get TWL working with my core context. Thing is, OGL 3 is all the OGL I know, so I don't know exactly how OpenGL 1 calls would be "translated".

 

I know only renderer>lwjgl has GL1.1 calls, which is a 2.5k line long package, so its not that bad (rest of the project is 35k line long or so).

 

So far I've seen a few matrix stack calls, attrib stack calls, calls for things I have no experience so far (textures, fixed function anti aliasing) and a few things that I don't quite know how to replace (GL_QUADS and GL_LINE_LOOP are deprecated in 3.3 i think).

 

As you probably notice, I'm not quite experienced yet. While I have gotten to the point of implementing soft per fragment shading with shader programs (with normals math and all that) there are quite a few spots I've jumped over without touching them (texturing being one of them). Besides the point that even if I manage to translate the GL11 calls, I don't how I would integrate the GUI library into my project (passing around my context to the GUI renderer I think?).

 

Do you think I'm biting more than I can handle? I know I could just create a compat context and see how it works but making the wrapper to 3.3 core sounds like a good learning experience. And while I don't have the time to do this right now (finals, exams, courses and all that good stuff) I'll probably want to do it in the near future. 

Edited by TheChubu

Share this post


Link to post
Share on other sites

Can't you just create your context with [tt]CONTEXT_COMPATIBILITY_PROFILE_BIT[/tt]? This will ask for a compatibility context, which supports all deprecated functionality (including OpenGL 1.1), so you should be able to plug in this library without any modifications.

 

Although support for the compatibility profile is optional, I don't know a single implementor that doesn't support it (that's unlikely to happen any time soon, too). In fact, I remember a guy from nVidia holding a lecture once (some title like "What's new in OpenGL 3") which basically advised to always use it because your programs don't get any slower and most/all of the deprecated functionality is well-supported in hardware anyway, so there was no reason not to use it. I'm somewhat disinclined to agree with that statement, but if that's an official statement from an IHV, then that's what it is. They gotta know better than you and me.

 

Found it, that "nVidia guy" was Mark Kilgard, see page 97:

Lots of easy-to-use, effective API got labeled deprecated [...] Best advice for real developers: Simply use the “compatibility” profile.

No, your program won’t go faster for using the “core” profile. It may go slower because of extra “is this allowed to work?” checks.

Edited by samoth

Share this post


Link to post
Share on other sites

Can't you just create your context with [tt]CONTEXT_COMPATIBILITY_PROFILE_BIT[/tt]?

 

 

This is a quote, the editor just bricks it when I press backspace for some reason:

 

"Do you think I'm biting more than I can handle? I know I could just create a compat context and see how it works but making the wrapper to 3.3 core sounds like a good learning experience."

 

Basically that. I know that a compatibility context doesn't affects your performance (I believe Valve stated that in their GDC presentation on OpenGL recently) . I was asking if I you thought I could make it with my current experience (probably not glMaterial for example) and if you could make any recommendation.

 

I thought of checking all the GL11 calls TWL does, categorize them and see what kind of structures I'd need to support them (matrix stack for glMatrix, some boolean state flags, buffers to hold glVertex call data, and so on) and slap everything in a single class with static methods, replacing the "GL11.glVertex" call with "wrapper.glVertex" or something like that (I thought of AGL.glVertex but AGL is already Apple's naming scheme for OpenGL calls heh).

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