/*
 * common/trilib.c 
 *
 * library for loading triangles from an Alias triangle file
 *
 */

#include <stdio.h>
#include <common/cmdlib.h>
#include <common/mathlib.h>
#include <common/trilib.h>

/* on disk representation of a face */

#define FLOAT_START  99999.0
#define FLOAT_END    -FLOAT_START
#define MAGIC        123322

/* #define NOISY 1 */

typedef struct {
    float v[3];
} vector;

typedef struct {
    vector n;                   /* normal */
    vector p;                   /* point */
    vector c;                   /* color */
    float u;                    /* u */
    float v;                    /* v */
} aliaspoint_t;

typedef struct {
    aliaspoint_t pt[3];
} tf_triangle;

void
ByteSwapTri(tf_triangle * tri)
{
    int i;

    for (i = 0; i < sizeof(tf_triangle) / 4; i++) {
        ((int *)tri)[i] = BigLong(((int *)tri)[i]);
    }
}

void
LoadTriangleList(char *filename, triangle_t ** pptri, int *numtriangles)
{
    FILE *input;
    float start;
    char name[256], tex[256];
    int i, count, magic;
    tf_triangle tri;
    triangle_t *ptri;
    int iLevel;
    int exitpattern;
    float t;

    t = -FLOAT_START;
    *((unsigned char *)&exitpattern + 0) = *((unsigned char *)&t + 3);
    *((unsigned char *)&exitpattern + 1) = *((unsigned char *)&t + 2);
    *((unsigned char *)&exitpattern + 2) = *((unsigned char *)&t + 1);
    *((unsigned char *)&exitpattern + 3) = *((unsigned char *)&t + 0);

    if ((input = fopen(filename, "rb")) == 0) {
        fprintf(stderr, "reader: could not open file '%s'\n", filename);
        exit(0);
    }

    iLevel = 0;

    fread(&magic, sizeof(int), 1, input);
    if (BigLong(magic) != MAGIC) {
        fprintf(stderr, "File is not a Alias object separated triangle file,"
                " magic number is wrong.\n");
        exit(0);
    }

    ptri = malloc(MAXTRIANGLES * sizeof(triangle_t));

    *pptri = ptri;

    while (feof(input) == 0) {
        fread(&start, sizeof(float), 1, input);
        *(int *)&start = BigLong(*(int *)&start);

        if (*(int *)&start != exitpattern) {
            if (start == FLOAT_START) {
                /* Start of an object or group of objects. */
                i = -1;
                do {
                    /* There are probably better ways to read a string from */
                    /* a file, but this does allow you to do error checking */
                    /* (which I'm not doing) on a per character basis.      */
                    ++i;
                    fread(&(name[i]), sizeof(char), 1, input);
                } while (name[i] != '\0');

                /*            indent();                                                 */
                /*            fprintf(stdout,"OBJECT START: %s\n",name);                */
                fread(&count, sizeof(int), 1, input);
                count = BigLong(count);
                ++iLevel;
                if (count != 0) {
                    /*                indent();                                             */

                    /*                fprintf(stdout,"NUMBER OF TRIANGLES: %d\n",count);    */

                    i = -1;
                    do {
                        ++i;
                        fread(&(tex[i]), sizeof(char), 1, input);
                    } while (tex[i] != '\0');

                    /*                indent();                                             */
                    /*                fprintf(stdout,"  Object texture name: '%s'\n",tex);  */
                }

                /* Else (count == 0) this is the start of a group, and */
                /* no texture name is present. */
            } else if (start == FLOAT_END) {
                /* End of an object or group. Yes, the name should be */
                /* obvious from context, but it is in here just to be */
                /* safe and to provide a little extra information for */
                /* those who do not wish to write a recursive reader. */
                /* Mia culpa. */
                --iLevel;
                i = -1;
                do {
                    ++i;
                    fread(&(name[i]), sizeof(char), 1, input);
                } while (name[i] != '\0');

                /*            indent();                                                 */
                /*            fprintf(stdout,"OBJECT END: %s\n",name);                  */
                continue;
            }
        }

        /* read the triangles */
        for (i = 0; i < count; ++i) {
            int j;

            fread(&tri, sizeof(tf_triangle), 1, input);
            ByteSwapTri(&tri);
            for (j = 0; j < 3; j++) {
                int k;

                for (k = 0; k < 3; k++) {
                    ptri->verts[j][k] = tri.pt[j].p.v[k];
                }
            }

            ptri++;

            if ((ptri - *pptri) >= MAXTRIANGLES)
                Error("Error: too many triangles; increase MAXTRIANGLES\n");
        }
    }

    *numtriangles = ptri - *pptri;

    fclose(input);
}