/*
    warp.c

    This is an example of what extreme field of view can do.....

*/
#include <stdlib.h>
#include <mgl/gl.h>

#include <math.h>
#ifndef M_PI
#define M_PI 3.14159265
#endif
#include <stdio.h>

GLint width=640; GLint height=480;
GLfloat startilt = 0.0;
GLfloat t_off = 0.0;
GLfloat fov = 170.0;

typedef struct
{
    GLfloat x,y,z,u,v;
} MyVertex;


GLubyte *LoadPPM(char *name, GLint *w, GLint *h)
{
    int i;
    unsigned long x,y;
    FILE *f;
    GLubyte *where;

    f = fopen(name, "r");

    if (!f)
    {
        *w = 0; *h=0;
        return NULL;
    }
    #ifndef __STORM__
    i = fscanf(f, "P6\n%ld %ld\n255\n",&x, &y);
    #else
    i = fscanf(f, "P6\n%ld\n%ld\n255\n", &x, &y);
    #endif

    if (i!= 2)
    {
        printf("Error scanning PPM header\n");
        fclose(f);
        *w = 0; *h = 0;
        return NULL;
    }

    *w = x;
    *h = y;

    where = malloc(x*y*3);
    if (!where)
    {
        printf("Error out of Memory\n");
        fclose(f);
        *w = 0; *h = 0;
        return NULL;
    }

    i = fread(where, 1, x*y*3, f);
    fclose(f);

    if (i != x*y*3)
    {
        printf("Error while reading file\n");
        free(where);
        *w = 0; *h = 0;
        return NULL;
    }

    return where;
}


BOOL TexInit(char *name, int num)
{
    GLubyte *tmap;
    GLint x,y;

    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
    glPixelStorei(GL_PACK_ALIGNMENT, 1);

    if (!name)
    {
        return FALSE;
    }
    else
    {
        tmap = LoadPPM(name, &x, &y);
    }

    if (!tmap)
        return FALSE;

    glBindTexture(GL_TEXTURE_2D, num);
    glTexImage2D(GL_TEXTURE_2D, 0, 3,
        x,y, 0, GL_RGB, GL_UNSIGNED_BYTE, tmap);
    free(tmap);

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

    glEnable(GL_TEXTURE_2D);

    return TRUE;
}

static void drawFlare(GLint texnum)
{
    GLfloat x,y,w,h;

    w=width/10.0;
    h=w;

    x=width/2.0-w/2.0;
    y=height/2.0-h/2.0;


    glBindTexture(GL_TEXTURE_2D, texnum);
    glEnable(GL_BLEND);
    glBlendFunc(GL_ONE, GL_ONE);
    /*
    ** An MGL_FLATFAN is a shortcut to draw something into the
    ** screen that does not go through the transformation pipeline.
    ** This is also not clipped, so you have to take care to avoid
    ** going over the edges, or clip yourself.
    */
    glBegin(MGL_FLATFAN);
        glTexCoord2f(0.0, 0.0);
        glVertex2f(x,y);
        glTexCoord2f(1.0, 0.0);
        glVertex2f(x+w, y);
        glTexCoord2f(1.0, 1.0);
        glVertex2f(x+w,y+h);
        glTexCoord2f(0.0, 1.0);
        glVertex2f(x,y+h);
    glEnd();
    glDisable(GL_BLEND);
}


static void drawStarField(GLint tex1, GLfloat off)
{
    GLfloat w = 1.0;
    #define BACKPLANE -8.0
    #define TEXTU 0.0
    #define TEXTV 2.0

    glBindTexture(GL_TEXTURE_2D, tex1);
    glBegin(GL_QUADS);

        glTexCoord2f(TEXTU, TEXTV+off);
        glVertex3f(-1.0,  1.0,  BACKPLANE);
        glTexCoord2f(TEXTU, off);
        glVertex3f(-1.0,  1.0,   1.0);
        glTexCoord2f(1.0, off);
        glVertex3f(-1.0, -1.0,   1.0);
        glTexCoord2f(1.0, TEXTV+off);
        glVertex3f(-1.0, -1.0,  BACKPLANE);

        glTexCoord2f(TEXTU, TEXTV+off);
        glVertex3f( 1.0,  1.0,  BACKPLANE);
        glTexCoord2f(TEXTU, off);
        glVertex3f( 1.0,  1.0,   1.0);
        glTexCoord2f(1.0, off);
        glVertex3f( 1.0, -1.0,   1.0);
        glTexCoord2f(1.0, TEXTV+off);
        glVertex3f( 1.0, -1.0,  BACKPLANE);

        glTexCoord2f(TEXTU, TEXTV+off);
        glVertex3f(-1.0,  1.0,  BACKPLANE);
        glTexCoord2f(TEXTU, off);
        glVertex3f(-1.0,  1.0,   1.0);
        glTexCoord2f(1.0, off);
        glVertex3f( 1.0,  1.0,   1.0);
        glTexCoord2f(1.0, TEXTV+off);
        glVertex3f( 1.0,  1.0,  BACKPLANE);

        glTexCoord2f(TEXTU, TEXTV+off);
        glVertex3f(-1.0, -1.0,  BACKPLANE);
        glTexCoord2f(TEXTU, off);
        glVertex3f(-1.0, -1.0,   1.0);
        glTexCoord2f(1.0, off);
        glVertex3f( 1.0, -1.0,   1.0);
        glTexCoord2f(1.0, TEXTV+off);
        glVertex3f( 1.0, -1.0,  BACKPLANE);

    glEnd();


}


void reshape(int w, int h)
{
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(70.0, 1.3333333, 1.0, 100.0);

    glMatrixMode(GL_MODELVIEW);
    glViewport(0, 0, w, h);
    glClearColor(0.0f, 0.f, 0.f, 1.f);
    glClearDepth(1.0);
}

void DoFrame(void)
{
    glClear(GL_DEPTH_BUFFER_BIT|GL_COLOR_BUFFER_BIT);

    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(fov, 1.3333333, 1.0, 100.0);

    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();

    glScalef(20.0, 20.0, 20.0);
    glRotatef(startilt, 0.0, 0.0, 1.0);
    glDisable(GL_CULL_FACE);

    drawStarField(1, t_off);
    drawFlare(2);

    startilt += 0.1;
    t_off += 0.007;

    mglSwitchDisplay();
}


void keys(char c)
{

    switch (c)
    {
        case 0x1b:
            mglExit();
            break;
        case '+':
            if (fov < 165.0)
                fov += 5.0;
            break;
        case '-':
            if (fov > 30)
                fov -= 5.0;
            break;
    }

}

int main(int argc, char *argv[])
{
    int i;
    char *filename = "data/stars.ppm";
    char *flarename = "data/flare.ppm";

    for (i=1; i<argc; i++)
    {
        if (0 == stricmp(argv[i], "-width"))
        {
            i++;
            width = atoi(argv[i]);
        }
        if (0 == stricmp(argv[i], "-height"))
        {
            i++;
            height = atoi(argv[i]);
        }
        if (0 == stricmp(argv[i], "-window"))
        {
            mglChooseWindowMode(GL_TRUE);
        }
        if (0 == stricmp(argv[i], "-texture"))
        {
            i++;
            filename = argv[i];
        }
        if (0 == stricmp(argv[i], "-flare"))
        {
            i++;
            flarename = argv[i];
        }
    }

    MGLInit();

    mglChooseVertexBufferSize(1000);
    mglChooseNumberOfBuffers(3);
    mglCreateContext(0,0,width,height);
    mglEnableSync(GL_FALSE);

    glClearColor(0.0, 0.0, 0.0, 0.0);
    reshape(width, height);
    glDisable(GL_DEPTH_TEST);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);


    if ( TexInit(filename, 1) && TexInit(flarename, 2) )
    {
        glClearColor(0.0, 0.0, 0.0, 1.0);
        glColor3f(1.0, 1.0, 1.0);
        glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

        glHint(MGL_W_ONE_HINT, GL_FASTEST);
        glEnable(GL_TEXTURE_2D);
        glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);


        mglLockMode(MGL_LOCK_SMART);
        mglIdleFunc(DoFrame);
        mglKeyFunc(keys);
        mglMainLoop();
    }
    else
    {
        printf("Can't load textures\n");
    }

    mglDeleteContext();
    MGLTerm();
    return 0;             /* ANSI C requires main to return int. */
}