dos-3D-Engine/src/part3D/engine.c

#include "defines.h"

fixed sintab[360], costab[360];
Point2D v_cache[MAX_VERTEX];

void mat3_identity(Matrix3 *mat) {
    memset(mat, 0, sizeof(Matrix3));
    mat->m[0][0] = mat->m[1][1] = mat->m[2][2] = int_to_f(1);
}

void init_engine_math(void) {
#ifndef MINIMAL_PLAYER
    int i;
    for (i = 0; i < 360; i++) {
        double r = (double)i * 3.14159265 / 180.0;
        sintab[i] = (fixed)(sin(r) * 65536.0);
        costab[i] = (fixed)(cos(r) * 65536.0);
    }
#endif
}

void mat3_mul(Matrix3 *res, Matrix3 *a, Matrix3 *b) {
    Matrix3 tmp;
    int i, j;
    for (i = 0; i < 3; i++)
        for (j = 0; j < 3; j++)
            tmp.m[i][j] = f_mul(a->m[i][0], b->m[0][j]) +
                          f_mul(a->m[i][1], b->m[1][j]) +
                          f_mul(a->m[i][2], b->m[2][j]);
    *res = tmp;
}

void mat3_rotate_x(Matrix3 *m, int angle) {
    int a = ((angle % 360) + 360) % 360;
    fixed c = costab[a], s = sintab[a];
    mat3_identity(m);
    m->m[1][1] = c;
    m->m[1][2] = -s;
    m->m[2][1] = s;
    m->m[2][2] = c;
}

void mat3_rotate_y(Matrix3 *m, int angle) {
    int a = ((angle % 360) + 360) % 360;
    fixed c = costab[a], s = sintab[a];
    mat3_identity(m);
    m->m[0][0] = c;
    m->m[0][2] = s;
    m->m[2][0] = -s;
    m->m[2][2] = c;
}

void mat3_rotate_z(Matrix3 *m, int angle) {
    int a = ((angle % 360) + 360) % 360;
    fixed c = costab[a], s = sintab[a];
    mat3_identity(m);
    m->m[0][0] = c;
    m->m[0][1] = s;
    m->m[1][0] = -s;
    m->m[1][1] = c;
}

/* Fait pivoter la géométrie locale de l'objet de façon permanente */
/*
void bake_object_rotation(Universe *uni, Object3D *obj, int ax, int ay, int az) {
    Matrix3 rx, ry, rz, tmp, rot;
    Vector3 *v, *n;

    int i, vi;
    fixed vx, vy, vz;

    if (!obj || !uni) return;

    /* Composition de la matrice de rotation * /
    mat3_rotate_x(&rx, ax);
    mat3_rotate_y(&ry, ay);
    mat3_rotate_z(&rz, az);
    mat3_mul(&tmp, &rx, &ry);
    mat3_mul(&rot, &tmp, &rz);

    /* Application à tous les sommets et normales de l'objet * /
    for (i = 0; i < obj->num_verts; i++) {
        vi = obj->vert_start + i;
        v = &uni->verts[vi];
        n = &uni->v_normals[vi];

        /* Sommets * /
        vx = f_mul(v->x, rot.m[0][0]) + f_mul(v->y, rot.m[1][0]) + f_mul(v->z, rot.m[2][0]);
        vy = f_mul(v->x, rot.m[0][1]) + f_mul(v->y, rot.m[1][1]) + f_mul(v->z, rot.m[2][1]);
        vz = f_mul(v->x, rot.m[0][2]) + f_mul(v->y, rot.m[1][2]) + f_mul(v->z, rot.m[2][2]);
        v->x = vx;
        v->y = vy;
        v->z = vz;

        /* Normales (doivent aussi pivoter pour l'ombrage Gouraud !) * /
        vx = f_mul(n->x, rot.m[0][0]) + f_mul(n->y, rot.m[1][0]) + f_mul(n->z, rot.m[2][0]);
        vy = f_mul(n->x, rot.m[0][1]) + f_mul(n->y, rot.m[1][1]) + f_mul(n->z, rot.m[2][1]);
        vz = f_mul(n->x, rot.m[0][2]) + f_mul(n->y, rot.m[1][2]) + f_mul(n->z, rot.m[2][2]);
        n->x = vx;
        n->y = vy;
        n->z = vz;
    }
}
*/
void render_universe(Universe *uni, Camera *cam, int mode) {
    int o, i, vi, front;
    fixed rx, ry, rz, pz, nz;
    uint8_t wire_col;
    Vector3 *v, *n;
    Object3D *obj;
    Face *f;
    Point2D *p1, *p2, *p3;

    for (o = 0; o < uni->num_objects; o++) {
        obj = &uni->objects[o];

        /* Transformation + projection de tous les sommets de cet objet */
        for (i = 0; i < obj->num_verts; i++) {
            vi = obj->vert_start + i;
            v  = &uni->verts[vi];
            n  = &uni->v_normals[vi];

            rx = f_mul(v->x, obj->rot.m[0][0]) + f_mul(v->y, obj->rot.m[1][0]) + f_mul(v->z, obj->rot.m[2][0]) + obj->pos.x - cam->pos.x;
            ry = f_mul(v->x, obj->rot.m[0][1]) + f_mul(v->y, obj->rot.m[1][1]) + f_mul(v->z, obj->rot.m[2][1]) + obj->pos.y - cam->pos.y;
            rz = f_mul(v->x, obj->rot.m[0][2]) + f_mul(v->y, obj->rot.m[1][2]) + f_mul(v->z, obj->rot.m[2][2]) + obj->pos.z - cam->pos.z;

            pz = (rz < int_to_f(20)) ? int_to_f(20) : rz;
            v_cache[vi].z = pz;
            v_cache[vi].x = 160 + f_to_int(f_div(rx << 8, pz));
            v_cache[vi].y = 100 - f_to_int(f_div(ry << 8, pz));

            nz = f_mul(n->x, obj->rot.m[0][2]) + f_mul(n->y, obj->rot.m[1][2]) + f_mul(n->z, obj->rot.m[2][2]);
            v_cache[vi].intensity = (nz >= 0) ? int_to_f(1) : f_mul(-nz, int_to_f(14)) + int_to_f(1);
        }

        wire_col = (uint8_t)((obj->color << 4) | 15);

        /* Rendu des faces */
        for (i = 0; i < obj->num_faces; i++) {
            f  = &uni->faces[obj->face_start + i];
            p1 = &v_cache[f->a];
            p2 = &v_cache[f->b];
            p3 = &v_cache[f->c];
            front = ((p2->x - p1->x) * (p3->y - p1->y) - (p2->y - p1->y) * (p3->x - p1->x)) > 0;

            switch (mode) {
                case MODE_WIRE:
                    draw_line_z(p1, p2, wire_col, 0);
                    draw_line_z(p2, p3, wire_col, 0);
                    draw_line_z(p3, p1, wire_col, 0);
                    break;
                case MODE_HIDDEN:
                    if (front) {
                        draw_line_z(p1, p2, wire_col, 1);
                        draw_line_z(p2, p3, wire_col, 1);
                        draw_line_z(p3, p1, wire_col, 1);
                    }
                    break;
                case MODE_SOLID:
                default:
                    if (front) {
                        if (f->force_wire) {
                            draw_line_z(p1, p2, wire_col, 1);
                            draw_line_z(p2, p3, wire_col, 1);
                            draw_line_z(p3, p1, wire_col, 1);
                        } else {
                            fill_triangle_gouraud(p1, p2, p3, obj->color);
                        }
                    }
                    break;
            }
        }
    }
}