//  ---------------------------------------------------------------------------
//
//  @file       TwSimpleGLFW.c
//  @brief      A simple example that uses AntTweakBar with 
//              OpenGL and the GLFW windowing system.
//
//              AntTweakBar: http://anttweakbar.sourceforge.net/doc
//              OpenGL:      http://www.opengl.org
//              GLFW:        http://www.glfw.org
//  
//  @author     Philippe Decaudin
//  @date       2006/05/20
//
//  ---------------------------------------------------------------------------


#include <AntTweakBar.h>

#define GLFW_DLL
#include "glfw.h"

#include <stdio.h>


// Callback function called by GLFW when window size changes
void GLFWCALL WindowSizeCB(int width, int height)
{
    // Set OpenGL viewport and camera
    glViewport(0, 0, width, height);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(40, (double)width/height, 1, 10);
    gluLookAt(-1,0,3, 0,0,0, 0,1,0);    
    
    // Send the new window size to AntTweakBar
    TwWindowSize(width, height);
}


// This example program draws a possibly transparent cube 
void DrawModel(int wireframe)
{
    int pass, numPass;

    // Enable OpenGL transparency and light (could have been done once at init)
    glEnable(GL_BLEND);
    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
    glEnable(GL_DEPTH_TEST);
    glEnable(GL_LIGHT0);    // use default light diffuse and position
    glLightModeli(GL_LIGHT_MODEL_TWO_SIDE, 1);
    glEnable(GL_COLOR_MATERIAL);
    glColorMaterial(GL_FRONT_AND_BACK, GL_DIFFUSE);
    glEnable(GL_LINE_SMOOTH);
    glLineWidth(3.0);
    
    if( wireframe )
    {
        glDisable(GL_CULL_FACE);    
        glDisable(GL_LIGHTING);
        glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
        numPass = 1;
    }
    else
    {
        glEnable(GL_CULL_FACE); 
        glEnable(GL_LIGHTING);
        glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
        numPass = 2;
    }

    for( pass=0; pass<numPass; ++pass )
    {
        // Since the material could be transparent, we draw the convex model in 2 passes:
        // first its back faces, and second its front faces.
        glCullFace( (pass==0) ? GL_FRONT : GL_BACK );

        // Draw the model (a cube)
        glBegin(GL_QUADS);
            glNormal3f(0,0,-1); glVertex3f(0,0,0); glVertex3f(0,1,0); glVertex3f(1,1,0); glVertex3f(1,0,0); // front face
            glNormal3f(0,0,+1); glVertex3f(0,0,1); glVertex3f(1,0,1); glVertex3f(1,1,1); glVertex3f(0,1,1); // back face
            glNormal3f(-1,0,0); glVertex3f(0,0,0); glVertex3f(0,0,1); glVertex3f(0,1,1); glVertex3f(0,1,0); // left face
            glNormal3f(+1,0,0); glVertex3f(1,0,0); glVertex3f(1,1,0); glVertex3f(1,1,1); glVertex3f(1,0,1); // right face
            glNormal3f(0,-1,0); glVertex3f(0,0,0); glVertex3f(1,0,0); glVertex3f(1,0,1); glVertex3f(0,0,1); // bottom face
            glNormal3f(0,+1,0); glVertex3f(0,1,0); glVertex3f(0,1,1); glVertex3f(1,1,1); glVertex3f(1,1,0); // top face
        glEnd();
    }
}


// Main
int main() 
{
    GLFWvidmode mode;   // GLFW video mode
    TwBar *bar;         // Pointer to a tweak bar
    
    double time = 0, dt;// Current time and enlapsed time
    double turn = 0;    // Model turn counter
    double speed = 0.3; // Model rotation speed
    int wire = 0;       // Draw model in wireframe?
    float bgColor[] = { 0.1f, 0.2f, 0.4f };         // Background color 
    unsigned char cubeColor[] = { 255, 0, 0, 128 }; // Model color (32bits RGBA)

    // Intialize GLFW   
    if( !glfwInit() )
    {
        // An error occured
        fprintf(stderr, "GLFW initialization failed\n");
        return 1;
    }

    // Create a window
    glfwGetDesktopMode(&mode);
    if( !glfwOpenWindow(640, 480, mode.RedBits, mode.GreenBits, mode.BlueBits, 
                        0, 16, 0, GLFW_WINDOW /* or GLFW_FULLSCREEN */) )
    {
        // A fatal error occured    
        fprintf(stderr, "Cannot open GLFW window\n");
        glfwTerminate();
        return 1;
    }
    glfwEnable(GLFW_MOUSE_CURSOR);
    glfwEnable(GLFW_KEY_REPEAT);
    glfwSetWindowTitle("AntTweakBar simple example using GLFW");

    // Initialize AntTweakBar
    TwInit(TW_OPENGL, NULL);

    // Create a tweak bar
    bar = TwNewBar("TweakBar");
    TwDefine(" GLOBAL help='This example shows how to integrate AntTweakBar with GLFW and OpenGL.' "); // Message added to the help bar.

    // Add 'speed' to 'bar': it is a modifable (RW) variable of type TW_TYPE_DOUBLE. Its key shortcuts are [s] and [S].
    TwAddVarRW(bar, "speed", TW_TYPE_DOUBLE, &speed, 
               " label='Rot speed' min=0 max=2 step=0.01 keyIncr=s keyDecr=S help='Rotation speed (turns/second)' ");

    // Add 'wire' to 'bar': it is a modifable variable of type TW_TYPE_BOOL32 (32 bits boolean). Its key shortcut is [w].
    TwAddVarRW(bar, "wire", TW_TYPE_BOOL32, &wire, 
               " label='Wireframe mode' key=w help='Toggle wireframe display mode.' ");

    // Add 'time' to 'bar': it is a read-only (RO) variable of type TW_TYPE_DOUBLE, with 1 precision digit
    TwAddVarRO(bar, "time", TW_TYPE_DOUBLE, &time, " label='Time' precision=1 help='Time (in seconds).' ");         

    // Add 'bgColor' to 'bar': it is a modifable variable of type TW_TYPE_COLOR3F (3 floats color)
    TwAddVarRW(bar, "bgColor", TW_TYPE_COLOR3F, &bgColor, " label='Background color' ");

    // Add 'cubeColor' to 'bar': it is a modifable variable of type TW_TYPE_COLOR32 (32 bits color) with alpha
    TwAddVarRW(bar, "cubeColor", TW_TYPE_COLOR32, &cubeColor, 
               " label='Cube color' alpha help='Color and transparency of the cube.' ");

    // Set GLFW event callbacks
    // - Redirect window size changes to the callback function WindowSizeCB
    glfwSetWindowSizeCallback(WindowSizeCB);
    // - Directly redirect GLFW mouse button events to AntTweakBar
    glfwSetMouseButtonCallback((GLFWmousebuttonfun)TwEventMouseButtonGLFW);
    // - Directly redirect GLFW mouse position events to AntTweakBar
    glfwSetMousePosCallback((GLFWmouseposfun)TwEventMousePosGLFW);
    // - Directly redirect GLFW mouse wheel events to AntTweakBar
    glfwSetMouseWheelCallback((GLFWmousewheelfun)TwEventMouseWheelGLFW);
    // - Directly redirect GLFW key events to AntTweakBar
    glfwSetKeyCallback((GLFWkeyfun)TwEventKeyGLFW);
    // - Directly redirect GLFW char events to AntTweakBar
    glfwSetCharCallback((GLFWcharfun)TwEventCharGLFW);


    // Initialize time
    time = glfwGetTime();

    // Main loop (repeated while window is not closed and [ESC] is not pressed)
    while( glfwGetWindowParam(GLFW_OPENED) && !glfwGetKey(GLFW_KEY_ESC) )
    {
        // Clear frame buffer using bgColor
        glClearColor(bgColor[0], bgColor[1], bgColor[2], 1);
        glClear( GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT );

        // Rotate model
        dt = glfwGetTime() - time;
        if( dt < 0 ) dt = 0;
        time += dt;
        turn += speed*dt;
        glMatrixMode(GL_MODELVIEW);
        glLoadIdentity();
        glRotated(360.0*turn, 0.4, 1, 0.2);
        glTranslated(-0.5, -0.5, -0.5);     
    
        // Set color and draw model
        glColor4ubv(cubeColor);
        DrawModel(wire);
        
        // Draw tweak bars
        TwDraw();

        // Present frame buffer
        glfwSwapBuffers();
    }

    // Terminate AntTweakBar and GLFW
    TwTerminate();
    glfwTerminate();

    return 0;
}