• Advertisement
Sign in to follow this  

OpenGL OpenGL in 10 days !?!?!

This topic is 2463 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 all,

As the topic says I really want to get the hang of OpenGL in 10 days. I am a newbie but trying to understand OpenGL for some months now. However I do not seem to get it and not confident to write program from scratch.

For now I want to get something working in OpenGL 2 and then move on to GLSL for my final project in the university.

Nehe tutorial ? or what resources on internet I should follow. I have ordered OpenGL superbible 5th edition from amazon so it should be in my hands in 4 days but I would like to know how you guys learned OpenGL programming ?

I want learn how to handle your own matrices ???, how does modeview matrix actually work. How to render and move things in 3D. I do not think I completely understand it TBH.

Please help

Share this post


Link to post
Share on other sites
Advertisement
its not going to be 10 days but rather at least a year:) (or more, from personal experience)
you might read the bible 5th edition in a month or so, but that's unlikely and even after reading you'll have to practice a LOT until you get comfortable with it and deal with your own ideas.
even after doing the aforementioned practice you'll likely run into lot of problems, that usually will come from not being experienced enough.
to add, if you aren't comfortable with C++ than it will likely take much longer time to accomplish this.

I'm not trying to persuade about don't start to learn OpenGL, but I'd like to emphasise that it will take a long-long time to get to the end of it

Share this post


Link to post
Share on other sites
NeHe is probably one of the faster ways to get something up and running, and it shouldn't take too long to make some working prototypes.

Actually completing a more advanced game, or learning all the internals, will take a long time. I wouldn't recommend starting with learning the math if you want to see quick results, unless you already have a very solid university math background.

Share this post


Link to post
Share on other sites
[quote name='playstation' timestamp='1302883778' post='4798822']
I want learn how to handle your own matrices ???, how does modeview matrix actually work. How to render and move things in 3D. I do not think I completely understand it TBH.
[/quote]

Two simplifications:
A matrix describes a coordinate system, the columns are x,y,z and origin. That's all there is to it (unless you add scaling or shearing). Don't worry about mathematical details of what happens when you multiply, just think "M = A*B" means "apply transformations in A after applying transformations in B". The result can still be directly read as coordinate system.

The mysterious w-coordinate on vectors can be thought of like this: w = 0 -> direction vector, w = 1 -> position vector (yes, it applies to matrices, the axes have w=0, the position/translation has w=1). If you do the math yourself you will see how it removes the translation part when multiplying with a matrix and when you look at GLs lighting model you will see how it makes the difference between a point light and a directional light.


More bla:
OpenGL is actually hiding stuff in a way that is both convenient and confusing. glRotate isn't magic, it just creates a rotationMatrix and does modelview = rotation * modelview. Same with glTranslate. D3D forces you to do it yourself, so you can't ignore what really happens. Seems more tedious, but ignorance isn't always bliss (look at the kind of questions arising from trying to achieve everything with these to glCursed functions). You want to forget about them if you handle your matrices yourself. If you don't move the point of view (or "camera", though technically such a thing doesn't exist) you can just directly glLoadMatrix your objects matrix and render it. Else you first need to apply the inverse of your "imaginary" camera's matrix (and yes, it simply transforms everything rendered afterwards -aka "the world"- in the opposite way).


"How to render and move things" suggests a wrong order. You can't move stuff after rendering it (it's just a bunch of pixels in the frame buffer now). First you setup your matrix to have it drawn in the right place, then you render. If you move it, you use a different matrix when drawing the next frame.

Share this post


Link to post
Share on other sites
Thanks for reply all. Yeah I will go through tutorials as it is defintely faster way to get things moving. Reading booking and practising will definitely take months.

[quote name='Trienco' timestamp='1302938888' post='4799054']
[quote name='playstation' timestamp='1302883778' post='4798822']
I want learn how to handle your own matrices ???, how does modeview matrix actually work. How to render and move things in 3D. I do not think I completely understand it TBH.
[/quote]

Two simplifications:
A matrix describes a coordinate system, the columns are x,y,z and origin. That's all there is to it (unless you add scaling or shearing). Don't worry about mathematical details of what happens when you multiply, just think "M = A*B" means "apply transformations in A after applying transformations in B". The result can still be directly read as coordinate system.

The mysterious w-coordinate on vectors can be thought of like this: w = 0 -> direction vector, w = 1 -> position vector (yes, it applies to matrices, the axes have w=0, the position/translation has w=1). If you do the math yourself you will see how it removes the translation part when multiplying with a matrix and when you look at GLs lighting model you will see how it makes the difference between a point light and a directional light.


More bla:
OpenGL is actually hiding stuff in a way that is both convenient and confusing. glRotate isn't magic, it just creates a rotationMatrix and does modelview = rotation * modelview. Same with glTranslate. D3D forces you to do it yourself, so you can't ignore what really happens. Seems more tedious, but ignorance isn't always bliss (look at the kind of questions arising from trying to achieve everything with these to glCursed functions). You want to forget about them if you handle your matrices yourself. If you don't move the point of view (or "camera", though technically such a thing doesn't exist) you can just directly glLoadMatrix your objects matrix and render it. Else you first need to apply the inverse of your "imaginary" camera's matrix (and yes, it simply transforms everything rendered afterwards -aka "the world"- in the opposite way).


"How to render and move things" suggests a wrong order. You can't move stuff after rendering it (it's just a bunch of pixels in the frame buffer now). First you setup your matrix to have it drawn in the right place, then you render. If you move it, you use a different matrix when drawing the next frame.
[/quote]

Thanks, I was looking at some matrixes and it is definetly confusing. OpenGL handles so I guess we do not have to worry about it. I like your example M= A*B and how OpenGL handle matrix in reverse order. I am not sure about the model and view matrix. Model handle from objecr space to world space and view from world spcae to eye space. It is confusing

Share this post


Link to post
Share on other sites
[quote name='playstation' timestamp='1303130608' post='4799854']
Thanks, I was looking at some matrixes and it is definetly confusing. OpenGL handles so I guess we do not have to worry about it. I like your example M= A*B and how OpenGL handle matrix in reverse order. I am not sure about the model and view matrix. Model handle from objecr space to world space and view from world spcae to eye space. It is confusing
[/quote]

If you're a university student try to take linear algebra, it helps alot.

Share this post


Link to post
Share on other sites
[quote name='playstation' timestamp='1302883778' post='4798822']
Nehe tutorial ? or what resources on internet I should follow. I have ordered OpenGL superbible 5th edition from amazon so it should be in my hands in 4 days but I would like to know how you guys learned OpenGL programming ?
[/quote]

Maybe you know this already, but be aware that NeHe uses the old fixed pipeline of OpenGL 2, but the Superbible 5th edition uses OpenGL 3.3. Assuming that you're just starting out, this can be very confusing because the book will not use most of the functions found in NeHe's tutorials as they are deprecated. Everything is done with shaders in the Superbible and that is why the author provides the GLtools library. Basically the GLtools is providing the functionality from OpenGL 2 that was deprecated in 3.3. I'm a beginner at OpenGL so It took me a bit to figure this out.

Share this post


Link to post
Share on other sites
[quote name='playstation' timestamp='1303130608' post='4799854']
I like your example M= A*B and how OpenGL handle matrix in reverse order.[/quote]
OpenGL doesn't handle matrices in reverse order. (If you're referring to the transforms being applied in the order B->A rather than A->B, this is simply a consequence of the fact that most OpenGL references use column-vector notation. But, it's not 'reversed' with respect to anything in particular.)

Share this post


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

  • Advertisement
  • Advertisement
  • Popular Now

  • Advertisement
  • Similar Content

    • By reenigne
      For those that don't know me. I am the individual who's two videos are listed here under setup for https://wiki.libsdl.org/Tutorials
      I also run grhmedia.com where I host the projects and code for the tutorials I have online.
      Recently, I received a notice from youtube they will be implementing their new policy in protecting video content as of which I won't be monetized till I meat there required number of viewers and views each month.

      Frankly, I'm pretty sick of youtube. I put up a video and someone else learns from it and puts up another video and because of the way youtube does their placement they end up with more views.
      Even guys that clearly post false information such as one individual who said GLEW 2.0 was broken because he didn't know how to compile it. He in short didn't know how to modify the script he used because he didn't understand make files and how the requirements of the compiler and library changes needed some different flags.

      At the end of the month when they implement this I will take down the content and host on my own server purely and it will be a paid system and or patreon. 

      I get my videos may be a bit dry, I generally figure people are there to learn how to do something and I rather not waste their time. 
      I used to also help people for free even those coming from the other videos. That won't be the case any more. I used to just take anyone emails and work with them my email is posted on the site.

      I don't expect to get the required number of subscribers in that time or increased views. Even if I did well it wouldn't take care of each reoccurring month.
      I figure this is simpler and I don't plan on putting some sort of exorbitant fee for a monthly subscription or the like.
      I was thinking on the lines of a few dollars 1,2, and 3 and the larger subscription gets you assistance with the content in the tutorials if needed that month.
      Maybe another fee if it is related but not directly in the content. 
      The fees would serve to cut down on the number of people who ask for help and maybe encourage some of the people to actually pay attention to what is said rather than do their own thing. That actually turns out to be 90% of the issues. I spent 6 hours helping one individual last week I must have asked him 20 times did you do exactly like I said in the video even pointed directly to the section. When he finally sent me a copy of the what he entered I knew then and there he had not. I circled it and I pointed out that wasn't what I said to do in the video. I didn't tell him what was wrong and how I knew that way he would go back and actually follow what it said to do. He then reported it worked. Yea, no kidding following directions works. But hey isn't alone and well its part of the learning process.

      So the point of this isn't to be a gripe session. I'm just looking for a bit of feed back. Do you think the fees are unreasonable?
      Should I keep the youtube channel and do just the fees with patreon or do you think locking the content to my site and require a subscription is an idea.

      I'm just looking at the fact it is unrealistic to think youtube/google will actually get stuff right or that youtube viewers will actually bother to start looking for more accurate videos. 
    • 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?
  • Advertisement