Javascript Ray Caster

Filed under Notes on December 9 | 0 comments

Using the new javacript canvas element, someone put together a simple ray caster.

GL_ARB_depth_texture

Filed under Notes on December 8 | 0 comments

OpenGL Extensions allow us to use graphics hardware without delving into many specifics. The first one we will look at is fairly easy to use and understand, and it is a requirement for other extensions that do much more interesting manipulations. GL_ARB_depth_texture allows us to create a texture from the depth component of the scene. This will allow us to do shadow maps later on.

Set Up

In this example I will be using OglExt, but there are many different extension managers out there and all are easy to use. I like OglExt because it doesn’t require an initialization step like the OpenGL Extension Wrangler requires. I will also be using GLWindow as it is an easy to use OpenGL framework. This example works just as well in GLUT or any other window manager you can find. Here is the main file that we will be working with. Each step is outlined.

#include “GLWindow.h”
#include <GL/gl.h>
#include <GL/glu.h>
#include <GL/glaux.h>
#include <GL/OglExt.h>

#define SIZE 512

class DepthTexture : public GLWindow
{
public:
    GLuint texture;

    bool init()
    {
        // Check that extension is supported

        // Create texture
        // Make texture active
        // Fiddle with texture parameters

        // Initialize texture memory using DEPTH_TEXTURE for internal format and format

        return true;
    }

    void draw()
    {      
        // clear the depth and color buffers
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
        glLoadIdentity();

        // Set viewpoint
       
        // Draw scene that we will take the depth of

        // Copy the current depth buffer to the texture

        // clear the depth and color buffers
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
        glLoadIdentity();

        // Set viewpoint
        // Draw a quad with the texture attached
    }
};

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
    DepthTexture* window = new DepthTexture();

    // Set Window size
    window->starting_width = SIZE;
    window->starting_height = SIZE;
    window->mainLoop(hInstance, hPrevInstance, lpCmdLine, nCmdShow);
}

Read more about GL_ARB_depth_texture

NVSG 2.1.0.9 Released

Filed under Notes on December 8 | 0 comments

Download it from the NVSG SDK page at NVidia’s website.

GLWindow

Filed under OpenGL on December 5 | 0 comments

Download GLWindow

Before we do any hardcore OpenGL programming, we need a framework for creating a window. Sure, you could use SDL or GLUT, but I want to play around with Win32. For that, we shall go to the old standard and copy NeHe’s code. Lesson 45 has a very nice example, but that’s C code. Let’s modify that to make it C++ worthy and create a GLWindow class. So, if you download NeHe’s Win32 code, you’ll see a lot of similarities to GLWindow, but I also made my own modifications

The GLWindow class is meant to be an easy to use framework for setting up an OpenGL project in no time. It allows access to most aspects of the code, making it easily expanded. The main workflow consists of subclassing GLWindow and overriding some of it’s virtual methods. Defaults are provided, so there is no need to override all of the methods. Once a subclass is defined, you instantiate it and call mainloop() to run the program. Piece of cake. Here’s the class structure.

class GLWindow
{
public:
    GLWindow();
    ~GLWindow(void);

    void redirectIOToConsole();
    void terminateApplication();
    void toggleFullscreen();
    bool changeScreenResolution(int width, int height, int bitsPerPixel);
    bool createWindow();
    bool destroyWindow();
    LRESULT CALLBACK windowProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam);
    bool registerWindowClass();
    void mainLoop(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow);

    virtual bool init();
    virtual void deinit();
    virtual void update(DWORD elapsedTime);
    virtual void draw();
    virtual void reshape(int width, int height);
    virtual bool handleMessage(UINT uMsg, WPARAM wParam, LPARAM lParam);

    virtual void onLMouseDown();
    virtual void onLMouseUp();
    virtual void onMMouseDown();
    virtual void onMMouseUp();
    virtual void onRMouseDown();
    virtual void onRMouseUp();
    virtual void onMouseMove(int x, int y, WPARAM keys);
    virtual void onMouseWheel(WPARAM keys, int wheelDelta, int x, int y);

    char title[256];
    int starting_width, current_width;
    int starting_height, current_height;
    int bitsPerPixel;
    bool isFullScreen;

protected:
    HINSTANCE hInstance;
    HWND hWnd;
    HDC hDC;
    HGLRC hRC;
    char className[64];

    bool isProgramLooping;
    bool createFullscreen;
    bool isMessagePumpActive;

    bool isVisible;
    DWORD lastTickCount;

    bool keys[256];

private:
    void sethWnd(HWND hWND) ;
    static LRESULT CALLBACK staticWindowProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam);
};
 

See the rest of GLWindow

OpenGL Extension Helpers

Filed under OpenGL on December 3 | 0 comments

A short list of OpenGL extension libraries