From: David Jenkins <me AT jenkinsdavid DOT demon DOT co DOT uk>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Allegros quad3d function HELP NEEDED.   PLEASE ;-)
Date: Sun, 16 Mar 1997 06:52:19 +0000
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Message-ID: <RHE9cJAji5KzEw2q@jenkinsdavid.demon.co.uk>
References: <tQhk9AA8R4HzEwpx AT jenkinsdavid DOT demon DOT co DOT uk>
 <or1VzBAaUjKzEwS2 AT jenkinsdavid DOT demon DOT co DOT uk>
 <bihl$LAZFsKzEwE2 AT talula DOT demon DOT co DOT uk>
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To: djgpp AT delorie DOT com
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In article <bihl$LAZFsKzEwE2 AT talula DOT demon DOT co DOT uk>, Shawn Hargreaves
<Shawn AT talula DOT demon DOT co DOT uk> writes
>David Jenkins writes:
>>Could somebody send me 2 source files.
>>1-With just one simple quad3d() face drawn on the screen.
>>
>>No rotation or anything just the most SIMPLE way to get a quad3d face
>>drawn onto a screen.
>
>Here's a really basic quad drawer. You might also want to have a look at
>the excellent 3d tutorial by Tero Parvinen, which can be found on 
>http://www.niksula.cs.hut.fi/~tparvine/allegro3d/.
>
>
>#include <allegro.h>
>
>int main()
>{
>   /* Declare four vertices defining the corners of the quad. In a real
>    * program these would of course be calculated on the fly, rather 
Why doesn't the following work???
Sorry about the mess. ;-) It's just something of my own I've hacked
apart to try the quad3d_f() functions.


#include <stdio.h>
#include <allegro.h>
#include <math.h>
#include <time.h>

#define  NUM_POINTS 4
#define  CENT_X 160
#define  CENT_Y 100
#define  SPEED 1
#define  LENS 256


void            init_display();
void            define_cube();
void            draw_cube();
void            rotatexyz(int, float, float);


struct points {
    float           x,
                    y,
                    z;
}              *current, *plotted;


struct act2d {
    float           x,
                    y;
};
    struct act2d v2d[4];

BITMAP         *buffer;

float           angle = 0.1;

void            init_display()
{
    int             d;
    PALLETE         pal;
    pal[0].r = 0;
    pal[0].g = 0;
    pal[0].b = 0;
    pal[1].r = 0;
    pal[1].g = 63;
    pal[1].b = 0;

    allegro_init();
    set_gfx_mode(GFX_VGA, 320, 200, 0, 0);
    set_pallete(pal);
    buffer = create_bitmap(SCREEN_W, SCREEN_H);
    install_keyboard();

}

void            define_cube()
{
    int             dum1;
current[0].x = -50;
current[0].y = -50;
current[0].z = -50;

current[1].x = 50;
current[1].y = -50;
current[1].z = -50;

current[2].x = 50;
current[2].y = 50;
current[2].z = -50;

current[3].x = -50;
current[3].y = 50;
current[3].z = -50;
}

void            draw_cube()
{
    int             d;
    float           dist,
                    cos_a,
                    sin_a;

    angle += 0.01;
    if (angle > 6.28)
        angle = 0;
    cos_a = cos(angle);
    sin_a = sin(angle);

    for (d = 0 ;  d < NUM_POINTS ; d++) {
        rotatexyz(d, cos_a, sin_a);

        dist = 256 - plotted[d].z;
        v2d[d].x = CENT_X - (LENS * plotted[d].x / dist);
        v2d[d].y = CENT_Y - (LENS * plotted[d].y / dist);
    }


/***************
This is where I get a "parse before vtx1 error".
*******/
    V3D_f vtx1 = {  v2d[0].x, v2d[0].y,  0,   0,   0,   255   };
    V3D_f vtx2 = {  v2d[1].x, v2d[1].y,  0,   0,   0,   10    };
    V3D_f vtx3 = {  v2d[2].x, v2d[2].y,  0,   0,   0,   128   };
    V3D_f vtx4 = {  v2d[3].x, v2d[3].y,  0,   0,   0,   160   };

   quad3d_f(buffer, POLYTYPE_FLAT, NULL, &vtx1, &vtx2, &vtx3, &vtx4);
 
}

void            rotatexyz(int d, float cos_a, float sin_a)
{
    float           new_x,
                    new_y,
                    new_z,
                    old_x,
                    old_y,
                    old_z;
    old_x = current[d].x;
    old_y = current[d].y;
    old_z = current[d].z;

    // rotate x axis
    new_y = old_y * cos_a - old_z * sin_a;
    new_z = old_z * cos_a + old_y * sin_a;
    old_y = new_y;
    old_z = new_z;

    // rotate z axis
    new_x = old_x * cos_a - old_y * sin_a;
    plotted[d].y = old_y * cos_a + old_x * sin_a;
    old_x = new_x;

    // rotate y axis
    plotted[d].z = old_z * cos_a - old_x * sin_a;
    plotted[d].x = old_x * cos_a + old_z * sin_a;


}



int             main()
{
    char            tim[50];
    int             ti;

    current = malloc(sizeof(struct points) * NUM_POINTS);
    plotted = malloc(sizeof(struct points) * NUM_POINTS);
    init_display();
    define_cube();


    while (!keypressed()) {
        ti = uclock();
        draw_cube();
        sprintf(tim, "tim=%d", (int) uclock() - ti);
        textout(buffer, font, tim, 0, 0, 1);
        vsync();
        blit(buffer, screen, 0, 0, 0, 0, SCREEN_W, SCREEN_H);
        clear(buffer);
    }

    return 0;
}
-- 
http://www.jenkinsdavid.demo.co.uk for Newbie C programers and a larf. ;-)
David Jenkins