• Advertisement
Sign in to follow this  

OpenGL Resolution settings, screen behaving unexplainably

This topic is 2126 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

So I've been trying to get resolution setting to work correctly in my game for a while to no avail. I have a 16:9 ratio which I am trying to keep constant. I am using SDL with openGL. And here's my changing resolution class:

[CODE]#ifndef _RESOLUTION_CPP_
#define _RESOLUTION_CPP_

#include "Main.h"

class Resolution{

public:

static void ChangeResolution(SDL_Surface* Screen,int Width,int Height, bool FullScreen){
int Full = 0;
if(FullScreen){
Full = SDL_FULLSCREEN;
}
Screen = SDL_SetVideoMode(Width , Height, 32, SDL_HWSURFACE | SDL_GL_DOUBLEBUFFER | SDL_OPENGL| Full);

glClearColor(0, 0, 0, 0);
glClearDepth(1.0f);

glViewport(0, 0, Width, Height);

glMatrixMode(GL_PROJECTION);
glLoadIdentity();

//glOrtho(0, Width, Height, 0, 1, -1);
glOrtho(0, 960,540, 0, 1, -1);

glMatrixMode(GL_MODELVIEW);

glEnable(GL_TEXTURE_2D);

glLoadIdentity();
}

};

#endif[/CODE]


Now at first I had glOrtho set to scale along with the window size and view port, but that made me see more of the screen as the window size got larger, which wasn't what I wanted. So by setting the camera (glOrtho is like the camera right?) To a constant width and height I was able to always see the same portion of the screen. So far so good.

Now trying the game in window mode, everything works exactly as it should. The game's graphics scale, keeping the aspect ratio, and I always see the same portion of the screen.

Now trying full screen on a 5:4 monitor, this is what I get:

[img]http://i.stack.imgur.com/DtE8B.jpg[/img]

Left: 960x540--- Middle:1024x576--- Right:1200x675

As you can see, only the one in the middle is working as it should, it's stretched to fill the screen, but not stretched to destroy the aspect ratio. The one on the left is keeping it's aspect ratio, but not scaling enough.

The one on the right is getting stretched vertically and the aspect ratio is broken. Why is that? Why would it get stretched like that?
Also, how would I go about centering the screen so that, on the middle monitor, the would be a black space on top and bottom, not just one big one at top?

[i]Additional info:[/i]

When I try this on a 16:10 laptop, I get similar results with the screen not being scaled enough or not being centered, but it never stretched. Even setting it at a huge resolution of 1920,1080. It exactly scales more than the screen such that I only see a small part, but I'm guessing you can't really squeeze a 1920x1080 on a much smaller resolution.

[b]So my question is really: Why is the resolution thing being completely unpredictable? Sometimes it stretches, sometimes it doesn't scale enough, etc.. and how do I fix that?[/b]

Share this post


Link to post
Share on other sites
Advertisement
For each screen size you need to set up a custom glViewport parameters which can be done manually or by formula...
usage:
'Width' - a full-screen window width.
'Height' - a full-screen window heght.
example#1:
I want to do make my screen quadratic (adopting to window width and height) which aligned to center:
[code]
glViewport((Width-Height)/2,0,Height,Height); // I took 'Height' as minimal value, so I would have it work on displays which it's width is larget than height
[/code]
result will look like this:
+-------+--------------+-------+ < my display
|*******|...............|*******|
|*******|.......my...|*******|
|*******|..viewport..|*******|
|*******|...............|*******|
+-------+--------------+-------+
'*' - black pixel.
example#2:
I want to make my screen like film look (let say: 800x320) to get a result like watching a video (with these dimensions) in media player full-screen mode:
[code]
float aspectToY = 320.0f/800.0f;
int w = Width;
int h = int(float(w)*aspectToY); //!!! correct me if this is wrong.
glViewport(0, (Height - h) / 2, w, h); // NOTE: this would work if 'height'(ex:320) <= 'width'(ex:800).
[/code]
the result should be like this (for example if my display would be 800x600):
+---------------------------+ << my display
|************************|
+---------------------------+
|.............my...........|
|.........viewport........|
+---------------------------+
|************************|
+---------------------------+

extra information: OpenGL viewport coordinate system (for glViewport setup):
glViewport(x,y,width,height)
---------window top-------
^-height
|
|....+........+
|................\dimensions(width,height)
|....+........+
|......\offset (x,y)
------------------------> -width
---window bottom-----

As you see (in your screen-shots) screen always aligned on left-bottom corner.
Another thing can be happen:
when your display (monitor) first time using these WxH settings sometimes it could do some shift&amp;scale operation which produces strange screen results...
If this was happend, on LCD\LED monitors do: Menu->Settings->Reset:true

Best wishes, FXACE.

Share this post


Link to post
Share on other sites
Thank you for the very detailed post and explanation FXACE! I really really appreciate it!

So I've successful managed to get it to work like a movie, and it works perfectly in the window. However, back in full screen, I still game very similar results.

We know the viewport is working now, could it be something else? If it helps, when I try to move my mouse into the black bars in the full screen window, sometimes the mouse can't go there, other times it can.

I'm also curious about this part:

[i]Another thing can be happen:
when your display (monitor) first time using these WxH settings sometimes it could do some shift&amp;scale operation which produces strange screen results...
If this was happend, on LCD\LED monitors do: Menu->Settings->Reset:true[/i]

I'm on a laptop, I'm not sure if I have these settings.

Again, thank you very much for all the help so far (and in the other thread too!)

Share this post


Link to post
Share on other sites
[quote]

I'm also curious about this part:

Another thing can be happen:
when your display (monitor) first time using these WxH settings sometimes it could do some shift&amp;scale operation which produces strange screen results...
If this was happend, on LCD\LED monitors do: Menu->Settings->Reset:true

I'm on a laptop, I'm not sure if I have these settings.
[/quote]

From my own experience:
When I'm launching game application which enters to full-screen mode (640x480) on my monitors (LG FLATRONs 1920x1080 & 1680x1050) some part of game's screen becomes outside display or not fully stretched to entire display (some parts of screen are not used). If I would set Menu->Settings->Reset:true (on 640x480 mode) it would automatically, correctly changed (as I expect) and saves in monitor's memory (to load next time [b]shift/scale[/b] settings when switching to 640x480 again, this settings are customized and located in each resolution mode).

Labtops have some settings for display (accessed with 'fn' key) but I'm not sure do they have [b]these[/b] settings.

If you tested some full-screen applications (with modes:960x540, 1024x576, 1200x675) and they were correctly showed, so this is not a display issue.


I have no experience work with SDL(sorry) but I'm curious about this lines (from your code):
[code]

static void ChangeResolution(SDL_Surface* Screen,int Width,int Height, bool FullScreen)
..........
Screen = SDL_SetVideoMode(...)
[/code]
Is your 'Screen' an output variable too? If yes, you need to change from:
[code]
SDL_Surface* Screen // when calling a function with this argument instruct a pointer (which holds an address) would be dublicated
[/code]
to:
[code]
SDL_Surface* &Screen // with this your variable is now linked to input pointer
[/code]

Best wishes, FXACE.

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