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/* ______ ___ ___
* /\ _ \ /\_ \ /\_ \
* \ \ \L\ \\//\ \ \//\ \ __ __ _ __ ___
* \ \ __ \ \ \ \ \ \ \ /'__`\ /'_ `\/\`'__\/ __`\
* \ \ \/\ \ \_\ \_ \_\ \_/\ __//\ \L\ \ \ \//\ \L\ \
* \ \_\ \_\/\____\/\____\ \____\ \____ \ \_\\ \____/
* \/_/\/_/\/____/\/____/\/____/\/___L\ \/_/ \/___/
* /\____/
* \_/__/
*
* The 3D polygon clipper.
*
* By Calin Andrian.
*
* See readme.txt for copyright information.
*/
#include "allegro.h"
#define INT_NONE 0
#define INT_1COL 1
#define INT_3COL 2
#define INT_3COLP 4
#define INT_UV 8
/* point_inside:
* Copies a vertex to the output table.
*/
#define point_inside(vv) \
{ \
v3->x = v2->x; v3->y = v2->y; v3->z = v2->z; \
v3->u = v2->u; v3->v = v2->v; v3->c = v2->c; \
vv++; \
}
/* point_interp_f:
* Interpolates between v1 and v2, with slope "t", resulting vertex v3.
*/
#define point_interp_f(vv) \
{ \
v3->x = (v2->x - v1->x) * t + v1->x; \
v3->y = (v2->y - v1->y) * t + v1->y; \
v3->z = (v2->z - v1->z) * t + v1->z; \
\
if (flags & INT_1COL) { \
v3->c = (int)((v2->c - v1->c) * t + v1->c); \
} \
else if (flags & INT_3COLP) { \
int bpp = bitmap_color_depth(screen); \
int r = (int)((getr_depth(bpp, v2->c) - getr_depth(bpp, v1->c)) * t + getr_depth(bpp, v1->c)); \
int g = (int)((getg_depth(bpp, v2->c) - getg_depth(bpp, v1->c)) * t + getg_depth(bpp, v1->c)); \
int b = (int)((getb_depth(bpp, v2->c) - getb_depth(bpp, v1->c)) * t + getb_depth(bpp, v1->c)); \
v3->c = makecol_depth(bpp, r&255, g&255, b&255); \
} \
else if (flags & INT_3COL) { \
int r = (int)(((v2->c & 0xFF0000) - (v1->c & 0xFF0000)) * t + (v1->c & 0xFF0000)); \
int g = (int)(((v2->c & 0x00FF00) - (v1->c & 0x00FF00)) * t + (v1->c & 0x00FF00)); \
int b = (int)(((v2->c & 0x0000FF) - (v1->c & 0x0000FF)) * t + (v1->c & 0x0000FF)); \
v3->c = (r & 0xFF0000) | (g & 0x00FF00) | (b & 0x0000FF); \
} \
if (flags & INT_UV) { \
v3->u = (v2->u - v1->u) * t + v1->u; \
v3->v = (v2->v - v1->v) * t + v1->v; \
} \
vv++; \
}
/* clip3d_f:
* Clips a 3D polygon against planes x = -z, x = z, y = -z, y = z,
* z = min_z, z = max_z. If max_z <= min_z the z = max_z clipping is
* not done. Type is the rendering style - POLYTYPE_*, vc is the
* number of vertices, vtx contains the input vertices, vout will
* receive the result, vtmp and out must be supplied for temporary
* storage. The size of arrays vout, vtmp and out should be twice as
* big as vtx.
*/
int clip3d_f(int type, float min_z, float max_z, int vc, AL_CONST V3D_f *vtx[], V3D_f *vout[], V3D_f *vtmp[], int out[])
{
int i, j, vo, vt, flags;
float t;
V3D_f *v3;
AL_CONST V3D_f *v1, *v2, **vin;
static int flag_table[] = {
INT_NONE, /* flat */
INT_3COLP, /* gcol */
INT_3COL, /* grgb */
INT_UV, /* atex */
INT_UV, /* ptex */
INT_UV, /* atex mask */
INT_UV, /* ptex mask */
INT_UV + INT_1COL, /* atex lit */
INT_UV + INT_1COL, /* ptex lit */
INT_UV + INT_1COL, /* atex mask lit */
INT_UV + INT_1COL, /* ptex mask lit */
INT_UV, /* atex trans */
INT_UV, /* ptex trans */
INT_UV, /* atex mask trans */
INT_UV /* ptex mask trans */
};
type &= ~POLYTYPE_ZBUF;
flags = flag_table[type];
if (max_z > min_z) {
vt = 0;
for (i=0; i<vc; i++)
out[i] = (vtx[i]->z > max_z);
for (i=0, j=vc-1; i<vc; j=i, i++) {
v1 = vtx[j];
v2 = vtx[i];
v3 = vtmp[vt];
if ((out[j] & out[i]) != 0)
continue;
if ((out[j] | out[i]) == 0) {
point_inside(vt);
continue;
}
t = (max_z - v1->z) / (v2->z - v1->z);
point_interp_f(vt);
v3 = vtmp[vt];
if (out[j])
point_inside(vt);
}
vin = (AL_CONST V3D_f**)vtmp;
}
else {
vt = vc;
vin = vtx;
}
vo = 0;
for (i=0; i<vt; i++)
out[i] = (vin[i]->z < min_z);
for (i=0, j=vt-1; i<vt; j=i, i++) {
v1 = vin[j];
v2 = vin[i];
v3 = vout[vo];
if ((out[j] & out[i]) != 0)
continue;
if ((out[j] | out[i]) == 0) {
point_inside(vo);
continue;
}
t = (min_z - v1->z) / (v2->z - v1->z);
point_interp_f(vo);
v3 = vout[vo];
if (out[j])
point_inside(vo);
}
vt = 0;
for (i=0; i<vo; i++)
out[i] = (vout[i]->x < -vout[i]->z);
for (i=0, j=vo-1; i<vo; j=i, i++) {
v1 = vout[j];
v2 = vout[i];
v3 = vtmp[vt];
if ((out[j] & out[i]) != 0)
continue;
if ((out[j] | out[i]) == 0) {
point_inside(vt);
continue;
}
t = (-v1->z - v1->x) / (v2->x - v1->x + v2->z - v1->z);
point_interp_f(vt);
v3 = vtmp[vt];
if (out[j])
point_inside(vt);
}
vo = 0;
for (i=0; i<vt; i++)
out[i] = (vtmp[i]->x > vtmp[i]->z);
for (i=0, j=vt-1; i<vt; j=i, i++) {
v1 = vtmp[j];
v2 = vtmp[i];
v3 = vout[vo];
if ((out[j] & out[i]) != 0)
continue;
if ((out[j] | out[i]) == 0) {
point_inside(vo);
continue;
}
t = (v1->z - v1->x) / (v2->x - v1->x - v2->z + v1->z);
point_interp_f(vo);
v3 = vout[vo];
if (out[j])
point_inside(vo);
}
vt = 0;
for (i=0; i<vo; i++)
out[i] = (vout[i]->y < -vout[i]->z);
for (i=0, j=vo-1; i<vo; j=i, i++) {
v1 = vout[j];
v2 = vout[i];
v3 = vtmp[vt];
if ((out[j] & out[i]) != 0)
continue;
if ((out[j] | out[i]) == 0) {
point_inside(vt);
continue;
}
t = (-v1->z - v1->y) / (v2->y - v1->y + v2->z - v1->z);
point_interp_f(vt);
v3 = vtmp[vt];
if (out[j])
point_inside(vt);
}
vo = 0;
for (i=0; i<vt; i++)
out[i] = (vtmp[i]->y > vtmp[i]->z);
for (i=0, j=vt-1; i<vt; j=i, i++) {
v1 = vtmp[j];
v2 = vtmp[i];
v3 = vout[vo];
if ((out[j] & out[i]) != 0)
continue;
if ((out[j] | out[i]) == 0) {
point_inside(vo);
continue;
}
t = (v1->z - v1->y) / (v2->y - v1->y - v2->z + v1->z);
point_interp_f(vo);
v3 = vout[vo];
if (out[j])
point_inside(vo);
}
if (type == POLYTYPE_FLAT)
vout[0]->c = vtx[0]->c;
return vo;
}
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