• Announcements

    • khawk

      Download the Game Design and Indie Game Marketing Freebook   07/19/17

      GameDev.net and CRC Press have teamed up to bring a free ebook of content curated from top titles published by CRC Press. The freebook, Practices of Game Design & Indie Game Marketing, includes chapters from The Art of Game Design: A Book of Lenses, A Practical Guide to Indie Game Marketing, and An Architectural Approach to Level Design. The GameDev.net FreeBook is relevant to game designers, developers, and those interested in learning more about the challenges in game development. We know game development can be a tough discipline and business, so we picked several chapters from CRC Press titles that we thought would be of interest to you, the GameDev.net audience, in your journey to design, develop, and market your next game. The free ebook is available through CRC Press by clicking here. The Curated Books The Art of Game Design: A Book of Lenses, Second Edition, by Jesse Schell Presents 100+ sets of questions, or different lenses, for viewing a game’s design, encompassing diverse fields such as psychology, architecture, music, film, software engineering, theme park design, mathematics, anthropology, and more. Written by one of the world's top game designers, this book describes the deepest and most fundamental principles of game design, demonstrating how tactics used in board, card, and athletic games also work in video games. It provides practical instruction on creating world-class games that will be played again and again. View it here. A Practical Guide to Indie Game Marketing, by Joel Dreskin Marketing is an essential but too frequently overlooked or minimized component of the release plan for indie games. A Practical Guide to Indie Game Marketing provides you with the tools needed to build visibility and sell your indie games. With special focus on those developers with small budgets and limited staff and resources, this book is packed with tangible recommendations and techniques that you can put to use immediately. As a seasoned professional of the indie game arena, author Joel Dreskin gives you insight into practical, real-world experiences of marketing numerous successful games and also provides stories of the failures. View it here. An Architectural Approach to Level Design This is one of the first books to integrate architectural and spatial design theory with the field of level design. The book presents architectural techniques and theories for level designers to use in their own work. It connects architecture and level design in different ways that address the practical elements of how designers construct space and the experiential elements of how and why humans interact with this space. Throughout the text, readers learn skills for spatial layout, evoking emotion through gamespaces, and creating better levels through architectural theory. View it here. Learn more and download the ebook by clicking here. Did you know? GameDev.net and CRC Press also recently teamed up to bring GDNet+ Members up to a 20% discount on all CRC Press books. Learn more about this and other benefits here.
Sign in to follow this  
Followers 0
Timptation

OpenGL
Help with the basics...

12 posts in this topic

Why am I not seeing a red triangle on my blue screen?

 
 
#pragma comment(linker, "/subsystem:windows")
 
#include <windows.h>
#pragma comment (lib, "openGL32")
#include <gl/gl.h>
#include <gl/glu.h>
 
 
HDC g_HDC;
bool fullScreen = true;
 
void Render()
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
    glMatrixMode( GL_MODELVIEW );
    glLoadIdentity();
 
 
glColor4f(1.0f, 0.0f, 0.0f, 0.0f);
 
glPushMatrix();
glLoadIdentity();

glBegin(GL_POLYGON);
 
float zPos = -10.0f;
 
glVertex3f(100.0f, 100.0f, zPos);
glVertex3f(200.0f, 200.0f, zPos);
glVertex3f(300.0f, 100.0f, zPos);
 
glEnd();
    glPopMatrix();
 
    glFlush();
 
    // Bring back buffer to foreground
    SwapBuffers(g_HDC);
}
 
void SetupPixelFormat(HDC hDC)
{
    int nPixelFormat;
 
    static PIXELFORMATDESCRIPTOR pfd = {
            sizeof(PIXELFORMATDESCRIPTOR),          //size of structure
            1,                                      //default version
            PFD_DRAW_TO_WINDOW |                    //window drawing support
            PFD_SUPPORT_OPENGL |                    //opengl support
            PFD_DOUBLEBUFFER,                       //double buffering support
            PFD_TYPE_RGBA,                          //RGBA color mode
            32,                                     //32 bit color mode
            0, 0, 0, 0, 0, 0,                       //ignore color bits
            0,                                      //no alpha buffer
            0,                                      //ignore shift bit
            0,                                      //no accumulation buffer
            0, 0, 0, 0,                             //ignore accumulation bits
            16,                                     //16 bit z-buffer size
            0,                                      //no stencil buffer
            0,                                      //no aux buffer
            PFD_MAIN_PLANE,                         //main drawing plane
            0,                                      //reserved
            0, 0, 0 };                              //layer masks ignored
 
    nPixelFormat = ChoosePixelFormat(hDC, &pfd);

    SetPixelFormat(hDC, nPixelFormat, &pfd);
}
 
void InitOpenGL()
{

GLint iViewport[4];
    glGetIntegerv( GL_VIEWPORT, iViewport );
glViewport(0, 0, iViewport[2], iViewport[3]);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
    glOrtho( iViewport[0], iViewport[0]+iViewport[2], iViewport[1], iViewport[1]+iViewport[3], -100.0f, 100.0f );
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
 
glEnable(GL_DEPTH_TEST);
glFrontFace(GL_CW);
//glPolygonMode(GL_FRONT, GL_FILL);
glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
glDisable(GL_CULL_FACE);
 
glBlendFunc(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA);
//glEnable(GL_BLEND);
 
glClearColor(0.0f, 0.0f, 1.0f, 0.0f);
}
 
/*      Windows Event Procedure Handler */
LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    //      Rendering and Device Context variables are declared here.
    static HGLRC hRC;
    static HDC hDC;
 
    //      Width and Height for the window our robot is to be displayed in.
    int width, height;
 
    switch(message)
    {
            case WM_CREATE: //window being created
{
                    hDC = GetDC(hwnd);  //get current windows device context
                    g_HDC = hDC;
 
SetupPixelFormat(hDC); //call our pixel format setup function
 
                    //      Create rendering context and make it current
                    hRC = wglCreateContext(hDC);
                    wglMakeCurrent(hDC, hRC);
 
InitOpenGL();
 
                    return 0;
                    break;
}
            case WM_CLOSE:  //window is closing
{
                    /*      Deselect rendering context and delete it*/
                    wglMakeCurrent(hDC, NULL);
                    wglDeleteContext(hRC);
 
                    /*      Send quit message to queue*/
                    PostQuitMessage(0);
 
                    return 0;
                    break;
}
            case WM_SIZE:
{
                    /*      Retrieve width and height*/
                    height = HIWORD(lParam);
                    width = LOWORD(lParam);
 
                    /*      Don't want a divide by 0*/
                    if (height == 0)
                            height = 1;
 
                    /*      Reset the viewport to new dimensions*/
                    glViewport(0, 0, width, height);
 
                    /*      Set current Matrix to projection and load in the orthographic matrix*/
                    //glMatrixMode(GL_PROJECTION);
                    //glLoadIdentity(); //reset projection matrix
//glOrtho(...
 
                    //glMatrixMode(GL_MODELVIEW); //set modelview matrix
                    //glLoadIdentity(); //reset modelview matrix
 
                    return 0;
                    break;
}
            default:
{
                    break;
}
    }
 
    return (DefWindowProc(hwnd, message, wParam, lParam));
}
 
int APIENTRY WinMain(HINSTANCE hInstance,
                     HINSTANCE hPrevInstance,
                     LPSTR     lpCmdLine,
                     int       nCmdShow)
{
// Getting rid of unused variable warnings.
(nCmdShow);
(lpCmdLine);
(hPrevInstance);
 
    WNDCLASSEX windowClass;         //window class
    HWND    hwnd;                   //window handle
    MSG     msg = MSG();            //message
    bool    done;                   //flag for completion of app
    DWORD   dwExStyle;              //window extended style
    DWORD   dwStyle;                //window style
    RECT    windowRect;
 
    /*      Screen/display attributes*/
    int width = 2880;
    int height = 1800;
    int bits = 32;
 
    windowRect.left =(long)0;               //set left value to 0
    windowRect.right =(long)width; //set right value to requested width
    windowRect.top =(long)0;                //set top value to 0
    windowRect.bottom =(long)height; //set bottom value to requested height
 
    /*      Fill out the window class structure*/
    windowClass.cbSize              = sizeof(WNDCLASSEX);
    windowClass.style               = CS_HREDRAW | CS_VREDRAW;
    windowClass.lpfnWndProc         = WndProc;
    windowClass.cbClsExtra          = 0;
    windowClass.cbWndExtra          = 0;
    windowClass.hInstance           = hInstance;
    windowClass.hIcon               = LoadIcon(NULL, IDI_APPLICATION);
    windowClass.hCursor             = LoadCursor(NULL, IDC_ARROW);
    windowClass.hbrBackground       = NULL;
    windowClass.lpszMenuName        = NULL;
    windowClass.lpszClassName       = "MyClass";
    windowClass.hIconSm             = LoadIcon(NULL, IDI_WINLOGO);
 
    /*      Register window class*/
    if (!RegisterClassEx(&windowClass))
            return 0;
 
    /*      Check if fullscreen is on*/
    if (fullScreen)
    {
        DEVMODE dmScreenSettings;
        memset(&dmScreenSettings, 0, sizeof(dmScreenSettings));
        dmScreenSettings.dmSize = sizeof(dmScreenSettings);
        dmScreenSettings.dmPelsWidth = width;   //screen width
        dmScreenSettings.dmPelsHeight = height; //screen height
        dmScreenSettings.dmBitsPerPel = bits;   //bits per pixel
        dmScreenSettings.dmFields = DM_BITSPERPEL | DM_PELSWIDTH | DM_PELSHEIGHT;
 
        if( ChangeDisplaySettings(&dmScreenSettings, CDS_FULLSCREEN != DISP_CHANGE_SUCCESSFUL) )
        {
            /*      Setting display mode failed, switch to windowed*/
            MessageBox(NULL, "Display mode failed", NULL, MB_OK);
            fullScreen = false;
        }
    }
 
    /*      Check if fullscreen is still on*/
    if (fullScreen)
    {
        dwExStyle = WS_EX_APPWINDOW;    // window extended style
        dwStyle = WS_POPUP;             // windows style
        ShowCursor(FALSE);              // hide mouse pointer
    }
    else
    {
        dwExStyle = WS_EX_APPWINDOW | WS_EX_WINDOWEDGE; //window extended style
        dwStyle = WS_OVERLAPPEDWINDOW;                  //windows style
    }
 
    AdjustWindowRectEx(&windowRect, dwStyle, FALSE, dwExStyle);
 
    /*      Class registerd, so now create our window*/
    hwnd = CreateWindowEx(NULL, "MyClass", //class name
"2D_Project", //app name
dwStyle |
WS_CLIPCHILDREN |
WS_CLIPSIBLINGS,
0, 0, //x and y coords
windowRect.right - windowRect.left,
windowRect.bottom - windowRect.top, //width, height
NULL, //handle to parent
NULL, //handle to menu
hInstance, //application instance
NULL); //no xtra params
 
    /*      Check if window creation failed (hwnd = null ?)*/
    if (!hwnd)
return 0;
 
    ShowWindow(hwnd, SW_SHOW);      //display window
    UpdateWindow(hwnd);             //update window
 
    done = false;   //initialize loop condition variable
 
    /*      Main message loop*/
    while (!done)
    {
        PeekMessage(&msg, hwnd, NULL, NULL, PM_REMOVE);
 
        if (msg.message == WM_QUIT)     //did we receive a quit message?
        {
done = true;
}
        else
        {
            Render();
            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }
    }
 
    if (fullScreen)
    {
        ChangeDisplaySettings(NULL, 0);
        ShowCursor(TRUE);
    }
 
    return msg.wParam;
}
0

Share this post


Link to post
Share on other sites

Well... what exactly are you seeing at the moment? Also, use the code tags to format your post for code.

0

Share this post


Link to post
Share on other sites

Check this line :

 

glColor4f(1.0f, 0.0f, 0.0f, 0.0f);

 

How can you see anything when your alpha component is 0? Set it to 1 for opaque.

0

Share this post


Link to post
Share on other sites
I tried using <code></code>, but that didn't seem to do the trick. I can't seem to find the tags you're referring to. If you'll show me, I'll be more than happy to add the tags.

I thought the alpha channel was the other way around? Higher value for higher transparency. I haven't enabled GL_BLEND, so that shouldn't be an issue anyway, correct? I tried it with a 1, and I've verified glDisable(GL_BLEND) doesn't help either.

The only thing I see right now is a blue screen (the clear color). On occasion I can see red, but its not what I expect it to be in terms of size, then I keep messing around with code/values and lose it again... I feel like my ortho setup or camera knowledge is lacking somewher....
0

Share this post


Link to post
Share on other sites
WHAAAAT? That's really frustrating. I wonder if it has something to do with my machine. I'll try it on another one. I'm currently trying it on a dual booted macbook pro retina. Maybe apple's drivers aren't up to par or something...?
0

Share this post


Link to post
Share on other sites
Your screenshot gave me an idea.

Ok, I tried using

glVertex3f(0.0f, 200.0f, zPos);
glVertex3f(1600.0f, 900.0f, zPos);
glVertex3f(2800.0f, 200.0f, zPos);

because I have a 2800x1600 display. That way I had a better chance of seeing the triangle, since it would be larger, and I would expect to see the tip of the top be at my center screen, and bottom edges meet properly near the bottom edge of the screen. What I actually see (I'd post a screenshot if I knew the capture button...) is that the triangle tip is appearing roughly in the bottom right quadrant of my screen. Somewhere I must be getting bad values for screen size/viewport size/resolution/whatever.
0

Share this post


Link to post
Share on other sites
Also of note is that the thumbnail image of the program on my taskbar appears to be correct (maybe slightly off, but certainly different than what the fullscreen image is showing... A fullscreen issue then?
0

Share this post


Link to post
Share on other sites

The triangle appears where I'd expect it on my computer based on your projection matrix, vertex data and the screen resolution I am running. Try setting your projection matrix to identity (i.e. comment out the gOrtho line in InitOpenGL) and change your polygon draw calls to the following:

 

glVertex3f(-1.0f, -1.0f, 0);
glVertex3f(1.0f, -1.0f, 0);
glVertex3f(0.0f, 1.0f, 0);

You should see a big red triangle covering the entire screen (regardless of resolution) like this:

 

http://imgur.com/THV9H

0

Share this post


Link to post
Share on other sites
Doing that, I get a triangle with top at center screen, and bottom corners on the bottom of the screen at 1/4 and 3/4 screen width. The thumbnail image appears to have the triangle positioned such that the bottom left corner is at the bottom left of the image (as if at 0,0), top at (1/3 width, 2/3 height), and the bottom right corner at (2/3 width, 0). I'm still attempting to get this going on another machine too.....
0

Share this post


Link to post
Share on other sites
Ok, I just verified that everything is fine on another machine. I can only assume the issue has to do with apple's retina display tech. I know they have some kind of new resolution independence code that messes with how the drawing for the new display works. I won't claim to fully understand it, but it must be something to do with it. Their windows drivers must be doing something similar and keeping me from seeing what I expect to see.

The issue only appears in fullscreen mode. Development on this macbook will have to happen in windowed mode. If anyone has a solution, or even explanation, that would be great.

Thanks a bunch for your help GeneralQuery! Edited by fstim82
0

Share this post


Link to post
Share on other sites

Last I checked when researching some Wordpress graphics was that the retina technology takes an image with double the resolution (200% of the original) and reduces it, so you have more pixels per inch (I guess that would mean 4 pixels in the space 1 pixel normally takes up).

0

Share this post


Link to post
Share on other sites

Oh, I forgot to mention. Re: code tags. The correct usage is using square brackets rather than angle brackets, i.e.:

 

 

 
[code]type your code here[/code]
 

I wouldn't worry so much about it for your OP but it's useful to keep in mind for future posts as people with short attention spans (such as myself!) tend to zone out and hit the back button when confronted with a wall of unformatted code wink.png

0

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0

  • Similar Content

    • By Solid_Spy
      Hello, I have been working on SH Irradiance map rendering, and I have been using a GLSL pixel shader to render SH irradiance to 2D irradiance maps for my static objects. I already have it working with 9 3D textures so far for the first 9 SH functions.
      In my GLSL shader, I have to send in 9 SH Coefficient 3D Texures that use RGBA8 as a pixel format. RGB being used for the coefficients for red, green, and blue, and the A for checking if the voxel is in use (for the 3D texture solidification shader to prevent bleeding).
      My problem is, I want to knock this number of textures down to something like 4 or 5. Getting even lower would be a godsend. This is because I eventually plan on adding more SH Coefficient 3D Textures for other parts of the game map (such as inside rooms, as opposed to the outside), to circumvent irradiance probe bleeding between rooms separated by walls. I don't want to reach the 32 texture limit too soon. Also, I figure that it would be a LOT faster.
      Is there a way I could, say, store 2 sets of SH Coefficients for 2 SH functions inside a texture with RGBA16 pixels? If so, how would I extract them from inside GLSL? Let me know if you have any suggestions ^^.
    • By KarimIO
      EDIT: I thought this was restricted to Attribute-Created GL contexts, but it isn't, so I rewrote the post.
      Hey guys, whenever I call SwapBuffers(hDC), I get a crash, and I get a "Too many posts were made to a semaphore." from Windows as I call SwapBuffers. What could be the cause of this?
      Update: No crash occurs if I don't draw, just clear and swap.
      static PIXELFORMATDESCRIPTOR pfd = // pfd Tells Windows How We Want Things To Be { sizeof(PIXELFORMATDESCRIPTOR), // Size Of This Pixel Format Descriptor 1, // Version Number PFD_DRAW_TO_WINDOW | // Format Must Support Window PFD_SUPPORT_OPENGL | // Format Must Support OpenGL PFD_DOUBLEBUFFER, // Must Support Double Buffering PFD_TYPE_RGBA, // Request An RGBA Format 32, // Select Our Color Depth 0, 0, 0, 0, 0, 0, // Color Bits Ignored 0, // No Alpha Buffer 0, // Shift Bit Ignored 0, // No Accumulation Buffer 0, 0, 0, 0, // Accumulation Bits Ignored 24, // 24Bit Z-Buffer (Depth Buffer) 0, // No Stencil Buffer 0, // No Auxiliary Buffer PFD_MAIN_PLANE, // Main Drawing Layer 0, // Reserved 0, 0, 0 // Layer Masks Ignored }; if (!(hDC = GetDC(windowHandle))) return false; unsigned int PixelFormat; if (!(PixelFormat = ChoosePixelFormat(hDC, &pfd))) return false; if (!SetPixelFormat(hDC, PixelFormat, &pfd)) return false; hRC = wglCreateContext(hDC); if (!hRC) { std::cout << "wglCreateContext Failed!\n"; return false; } if (wglMakeCurrent(hDC, hRC) == NULL) { std::cout << "Make Context Current Second Failed!\n"; return false; } ... // OGL Buffer Initialization glClear(GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT); glBindVertexArray(vao); glUseProgram(myprogram); glDrawElements(GL_TRIANGLES, indexCount, GL_UNSIGNED_SHORT, (void *)indexStart); SwapBuffers(GetDC(window_handle));  
    • By Tchom
      Hey devs!
       
      I've been working on a OpenGL ES 2.0 android engine and I have begun implementing some simple (point) lighting. I had something fairly simple working, so I tried to get fancy and added color-tinting light. And it works great... with only one or two lights. Any more than that, the application drops about 15 frames per light added (my ideal is at least 4 or 5). I know implementing lighting is expensive, I just didn't think it was that expensive. I'm fairly new to the world of OpenGL and GLSL, so there is a good chance I've written some crappy shader code. If anyone had any feedback or tips on how I can optimize this code, please let me know.
       
      Vertex Shader
      uniform mat4 u_MVPMatrix; uniform mat4 u_MVMatrix; attribute vec4 a_Position; attribute vec3 a_Normal; attribute vec2 a_TexCoordinate; varying vec3 v_Position; varying vec3 v_Normal; varying vec2 v_TexCoordinate; void main() { v_Position = vec3(u_MVMatrix * a_Position); v_TexCoordinate = a_TexCoordinate; v_Normal = vec3(u_MVMatrix * vec4(a_Normal, 0.0)); gl_Position = u_MVPMatrix * a_Position; } Fragment Shader
      precision mediump float; uniform vec4 u_LightPos["+numLights+"]; uniform vec4 u_LightColours["+numLights+"]; uniform float u_LightPower["+numLights+"]; uniform sampler2D u_Texture; varying vec3 v_Position; varying vec3 v_Normal; varying vec2 v_TexCoordinate; void main() { gl_FragColor = (texture2D(u_Texture, v_TexCoordinate)); float diffuse = 0.0; vec4 colourSum = vec4(1.0); for (int i = 0; i < "+numLights+"; i++) { vec3 toPointLight = vec3(u_LightPos[i]); float distance = length(toPointLight - v_Position); vec3 lightVector = normalize(toPointLight - v_Position); float diffuseDiff = 0.0; // The diffuse difference contributed from current light diffuseDiff = max(dot(v_Normal, lightVector), 0.0); diffuseDiff = diffuseDiff * (1.0 / (1.0 + ((1.0-u_LightPower[i])* distance * distance))); //Determine attenuatio diffuse += diffuseDiff; gl_FragColor.rgb *= vec3(1.0) / ((vec3(1.0) + ((vec3(1.0) - vec3(u_LightColours[i]))*diffuseDiff))); //The expensive part } diffuse += 0.1; //Add ambient light gl_FragColor.rgb *= diffuse; } Am I making any rookie mistakes? Or am I just being unrealistic about what I can do? Thanks in advance
    • By yahiko00
      Hi,
      Not sure to post at the right place, if not, please forgive me...
      For a game project I am working on, I would like to implement a 2D starfield as a background.
      I do not want to deal with static tiles, since I plan to slowly animate the starfield. So, I am trying to figure out how to generate a random starfield for the entire map.
      I feel that using a uniform distribution for the stars will not do the trick. Instead I would like something similar to the screenshot below, taken from the game Star Wars: Empire At War (all credits to Lucasfilm, Disney, and so on...).

      Is there someone who could have an idea of a distribution which could result in such a starfield?
      Any insight would be appreciated
    • By afraidofdark
      I have just noticed that, in quake 3 and half - life, dynamic models are effected from light map. For example in dark areas, gun that player holds seems darker. How did they achieve this effect ? I can use image based lighting techniques however (Like placing an environment probe and using it for reflections and ambient lighting), this tech wasn't used in games back then, so there must be a simpler method to do this.
      Here is a link that shows how modern engines does it. Indirect Lighting Cache It would be nice if you know a paper that explains this technique. Can I apply this to quake 3' s light map generator and bsp format ?
  • Popular Now