/*
gl_sky_clip.c
sky polygons
Copyright (C) 1996-1997 Id Software, Inc.
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to:
Free Software Foundation, Inc.
59 Temple Place - Suite 330
Boston, MA 02111-1307, USA
$Id: gl_sky_clip.c,v 1.1.1.1 2001/03/06 09:34:00 lordhavoc Exp $
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#ifdef HAVE_STRING_H
# include <string.h>
#endif
#ifdef HAVE_STRINGS_H
# include <strings.h>
#endif
#include <stdarg.h>
#include "console.h"
#include "glquake.h"
#include "sys.h"
#include "view.h"
extern qboolean skyloaded;
extern vec5_t skyvec[6][4];
#define BOX_WIDTH 2056
/* cube face to sky texture offset conversion */
static const int skytex_offs[] = { 3, 0, 4, 1, 2, 5 };
/* clockwise loop through the cube faces adjoining the current face */
static const int face_loop[6][5] = {
{1, 2, 4, 5, 1},
{0, 5, 3, 2, 0},
{0, 1, 3, 4, 0},
{1, 5, 4, 2, 1},
{0, 2, 3, 5, 0},
{0, 4, 3, 1, 0},
};
/* convert axis and face distance into face */
static const int faces_table[3][6] = {
{-1, 0, 0, -1, 3, 3},
{-1, 4, 4, -1, 1, 1},
{-1, 2, 2, -1, 5, 5},
};
/* convert face magic bit mask to index into visit array */
static const int faces_bit_magic[] = { 2, 1, -1, 0, 3, -1, 4, -1 };
/* axis the cube face cuts (also index into vec3_t and n % 3 for 0 <= n < 6) */
static const int face_axis[] = { 0, 1, 2, 0, 1, 2 };
/* offset on the axis the cube face cuts */
static const vec_t face_offset[] = { 1024, 1024, 1024, -1024, -1024, -1024 };
/* cube face */
struct face_def {
int tex; // texture to bind to
glpoly_t poly; // describe the polygon of this face
float verts[32][VERTEXSIZE];
};
struct visit_def {
int face; // face being visited
int leave; // vertex departed through
};
/* our cube */
struct box_def {
/* keep track of which cube faces we visit and in what order */
struct visit_def visited_faces[9];
int face_visits[6];
int face_count;
/* the cube faces */
struct face_def face[6];
};
/*
determine_face
return the face of the cube which v hits first
0 +x
1 +y
2 +z
3 -x
4 -y
5 -z
Also scales v so it touches that face.
*/
static int
determine_face (vec3_t v)
{
float a[3];
float m;
int i = 0;
m = a[0] = fabs (v[0]);
a[1] = fabs (v[1]);
a[2] = fabs (v[2]);
if (a[1] > m) {
m = a[1];
i = 1;
}
if (a[2] > m) {
m = a[2];
i = 2;
}
if (!m) {
Sys_Error ("%s speared by sky poly edge\n", name->string);
}
if (v[i] < 0)
i += 3;
VectorScale (v, 1024 / m, v);
return i;
}
/*
find_intersect (for want of a better name)
finds the point of intersection of the plane formed by the eye and the two
points on the cube and the edge of the cube defined by the two faces.
Currently, this will break if the two points are not on adjoining cube
faces (ie either on opposing faces or the same face).
The equation for the point of intersection of a line and a plane is:
(x - p).n
y = x - _________ v
v.n
where n is the normal to the plane, p is a point on the plane, x is a
point on the line, and v is the direction vector of the line. n is found
by (x1 - e) cross (x2 - e) and p is taken to be e (e = eye coords) for
simplicity. However, because e is at 0,0,0, this simplifies to n = x1
cross x2 and p = 0,0,0, so the equation above simplifies to:
x.n
y = x - ___ v
v.n
*/
static int
find_intersect (int face1, vec3_t x1, int face2, vec3_t x2, vec3_t y)
{
vec3_t n; // normal to the plane formed by the
// eye and the two points on the cube.
vec3_t x = { 0, 0, 0 }; // point on cube edge of adjoining
// faces. always on an axis plane.
vec3_t v = { 0, 0, 0 }; // direction vector of cube edge.
// always +ve
vec_t x_n, v_n; // x.n and v.n
int axis;
vec3_t t;
x[face_axis[face1]] = face_offset[face1];
x[face_axis[face2]] = face_offset[face2];
axis = 3 - ((face_axis[face1]) + (face_axis[face2]));
v[axis] = 1;
CrossProduct (x1, x2, n);
x_n = DotProduct (x, n);
v_n = DotProduct (v, n);
VectorScale (v, x_n / v_n, t);
VectorSubtract (x, t, y);
return axis;
}
/*
find_cube_vertex
get the coords of the vertex common to the three specified faces of the
cube. NOTE: this WILL break if the three faces do not share a common
vertex. ie works = ((face1 % 3 != face2 % 3)
&& (face2 % 3 != face3 % 3)
&& (face1 % 3 != face3 % 3))
*/
static void
find_cube_vertex (int face1, int face2, int face3, vec3_t v)
{
v[face_axis[face1]] = face_offset[face1];
v[face_axis[face2]] = face_offset[face2];
v[face_axis[face3]] = face_offset[face3];
}
/*
set_vertex
add the vertex to the polygon describing the face of the cube. Offsets
the vertex relative to r_refdef.vieworg so the cube is always centered
on the player and also calculates the texture coordinates of the vertex
(wish I could find a cleaner way of calculating s and t).
*/
static void
set_vertex (struct box_def *box, int face, int ind, vec3_t v)
{
VectorCopy (v, box->face[face].poly.verts[ind]);
VectorAdd (v, r_refdef.vieworg, box->face[face].poly.verts[ind]);
switch (face) {
case 0:
box->face[face].poly.verts[ind][3] = (1024 - v[1] + 4) / BOX_WIDTH;
box->face[face].poly.verts[ind][4] = (1024 - v[2] + 4) / BOX_WIDTH;
break;
case 1:
box->face[face].poly.verts[ind][3] = (1024 + v[0] + 4) / BOX_WIDTH;
box->face[face].poly.verts[ind][4] = (1024 - v[2] + 4) / BOX_WIDTH;
break;
case 2:
box->face[face].poly.verts[ind][3] = (1024 + v[0] + 4) / BOX_WIDTH;
box->face[face].poly.verts[ind][4] = (1024 + v[1] + 4) / BOX_WIDTH;
break;
case 3:
box->face[face].poly.verts[ind][3] = (1024 + v[1] + 4) / BOX_WIDTH;
box->face[face].poly.verts[ind][4] = (1024 - v[2] + 4) / BOX_WIDTH;
break;
case 4:
box->face[face].poly.verts[ind][3] = (1024 - v[0] + 4) / BOX_WIDTH;
box->face[face].poly.verts[ind][4] = (1024 - v[2] + 4) / BOX_WIDTH;
break;
case 5:
box->face[face].poly.verts[ind][3] = (1024 + v[0] + 4) / BOX_WIDTH;
box->face[face].poly.verts[ind][4] = (1024 - v[1] + 4) / BOX_WIDTH;
break;
}
}
/*
add_vertex
append a vertex to the poly vertex list.
*/
static void
add_vertex (struct box_def *box, int face, vec3_t v)
{
set_vertex (box, face, box->face[face].poly.numverts++, v);
}
/*
insert_cube_vertices
insert the given cube vertices into the vertex list of the poly in the
correct location.
*/
static void
insert_cube_vertices (struct box_def *box, struct visit_def visit, int count,
...)
{
int i;
vec3_t **v;
va_list args;
int face = visit.face;
int ind = visit.leave + 1;
#ifdef __BORLANDC__
// This is fix for borland alloca "feature" which fails to restore stack
// correcly if calling function doesn't have any references to local variables.
char dummy[5];
dummy[0]=0;
#endif
va_start (args, count);
v = (vec3_t **) alloca (count * sizeof (vec3_t *));
for (i = 0; i < count; i++) {
v[i] = va_arg (args, vec3_t *);
}
va_end (args);
if (ind == box->face[face].poly.numverts) {
// the vertex the sky poly left this cube fase through is very
// conveniently the last vertex of the face poly. this means we
// can just append the vetexen
for (i = 0; i < count; i++)
add_vertex (box, face, *v[i]);
} else {
// we have to insert the cube vertices into the face poly
// vertex list
glpoly_t *p = &box->face[face].poly;
int c = p->numverts - ind;
const int vert_size = sizeof (p->verts[0]);
memmove (p->verts[ind + count], p->verts[ind], c * vert_size);
p->numverts += count;
for (i = 0; i < count; i++)
set_vertex (box, face, ind + i, *v[i]);
}
}
/*
cross_cube_edge
add the vertex formed by the poly edge crossing the cube edge to the
polygon for the two faces on that edge. Actually, the two faces define
the edge :). The poly edge is going from face 1 to face 2 (for
enter/leave purposes).
*/
static void
cross_cube_edge (struct box_def *box, int face1, vec3_t v1, int face2,
vec3_t v2)
{
vec3_t l;
int axis;
int face = -1;
axis = find_intersect (face1, v1, face2, v2, l);
if (l[axis] > 1024)
face = axis;
else if (l[axis] < -1024)
face = axis + 3;
if (face >= 0) {
vec3_t x;
VectorAdd (v1, v2, x);
VectorScale (x, 0.5, x);
cross_cube_edge (box, face1, v1, face, x);
cross_cube_edge (box, face, x, face2, v2);
} else {
struct visit_def *visit = box->visited_faces;
visit[box->face_count - 1].leave = box->face[face1].poly.numverts;
visit[box->face_count].face = face2;
box->face_count++;
box->face_visits[face2]++;
add_vertex (box, face1, l);
add_vertex (box, face2, l);
}
}
/*
process_corners
egad, veddy complicated :)
*/
static void
process_corners (struct box_def *box)
{
struct visit_def *visit = box->visited_faces;
int max_visit = 0;
int i;
int center = -1;
if (visit[box->face_count - 1].face == visit[0].face) {
box->face_count--;
}
for (i = 0; i < 6; i++) {
if (max_visit < box->face_visits[i]) {
max_visit = box->face_visits[i];
center = i;
}
}
switch (box->face_count) {
case 1:
case 2:
case 8:
// no corners
return;
case 3:
// one corner, no edges
{
vec3_t v;
find_cube_vertex (visit[0].face, visit[1].face, visit[2].face,
v);
insert_cube_vertices (box, visit[0], 1, v);
insert_cube_vertices (box, visit[1], 1, v);
insert_cube_vertices (box, visit[2], 1, v);
}
break;
case 4:
if (max_visit > 1)
return;
if (abs (visit[2].face - visit[0].face) == 3
&& abs (visit[3].face - visit[1].face) == 3) {
// 4 vertices
int sum, diff;
vec3_t v[4];
sum =
visit[0].face + visit[1].face + visit[2].face +
visit[3].face;
diff = visit[1].face - visit[0].face;
sum %= 3;
diff = (diff + 6) % 6;
center = faces_table[sum][diff];
for (i = 0; i < 4; i++) {
find_cube_vertex (visit[i].face, visit[(i + 1) & 3].face,
center, v[i]);
add_vertex (box, center, v[i]);
}
for (i = 0; i < 4; i++)
insert_cube_vertices (box, visit[i], 2, v[i],
v[(i - 1) & 3]);
} else {
// 2 vertices
int l_f, t_f, r_f, b_f;
vec3_t v_l, v_r;
if (abs (visit[2].face - visit[0].face) == 3) {
l_f = 0;
t_f = 1;
r_f = 2;
b_f = 3;
} else if (abs (visit[3].face - visit[1].face) == 3) {
l_f = 1;
t_f = 2;
r_f = 3;
b_f = 0;
} else {
return;
}
find_cube_vertex (visit[l_f].face, visit[t_f].face,
visit[b_f].face, v_l);
find_cube_vertex (visit[r_f].face, visit[t_f].face,
visit[b_f].face, v_r);
insert_cube_vertices (box, visit[t_f], 2, v_r, v_l);
insert_cube_vertices (box, visit[b_f], 2, v_l, v_r);
insert_cube_vertices (box, visit[l_f], 1, v_l);
insert_cube_vertices (box, visit[r_f], 1, v_r);
}
break;
case 5:
if (max_visit > 1) {
// one vertex
vec3_t v;
for (i = 0; i < 4; i++) {
// don't need to check the 5th visit
if (visit[(i + 2) % 5].face == visit[(i + 4) % 5].face)
break;
}
find_cube_vertex (visit[i].face, visit[(i + 1) % 5].face,
visit[(i + 2) % 5].face, v);
insert_cube_vertices (box, visit[i], 1, v);
insert_cube_vertices (box, visit[(i + 1) % 5], 1, v);
insert_cube_vertices (box, visit[(i + 4) % 5], 1, v);
} else {
// 3 vertices
unsigned int sel =
(((abs (visit[2].face - visit[0].face) == 3) << 2) |
((abs (visit[3].face - visit[1].face) == 3) << 1)
| ((abs (visit[4].face - visit[2].face) == 3) << 0));
vec3_t v[3];
center = faces_bit_magic[sel];
// printf ("%02o %d %d %d %d %d %d\n", sel, center,
// visit[0].face,
// visit[1].face, visit[2].face, visit[3].face,
// visit[4].face);
for (i = 0; i < 3; i++)
find_cube_vertex (visit[center].face,
visit[(center + 1 + i) % 5].face,
visit[(center + 2 + i) % 5].face, v[i]);
insert_cube_vertices (box, visit[center], 3, v[0], v[1], v[2]);
insert_cube_vertices (box, visit[(center + 1) % 5], 1, v[0]);
insert_cube_vertices (box, visit[(center + 2) % 5], 2, v[1],
v[0]);
insert_cube_vertices (box, visit[(center + 3) % 5], 2, v[2],
v[1]);
insert_cube_vertices (box, visit[(center + 4) % 5], 1, v[2]);
}
break;
case 6:
if (max_visit > 2)
return;
for (i = 0; i < 5; i++) {
// don't need to check the last point
if (visit[(i + 3) % 6].face == visit[(i + 5) % 6].face
|| visit[(i + 2) % 6].face == visit[(i + 5) % 6].face)
break;
}
if (visit[(i + 3) % 6].face == visit[(i + 5) % 6].face) {
// adjacant vertices
vec3_t v[2];
find_cube_vertex (visit[i].face, visit[(i + 1) % 6].face,
visit[(i + 2) % 6].face, v[0]);
find_cube_vertex (visit[(i + 1) % 6].face,
visit[(i + 2) % 6].face,
visit[(i + 3) % 6].face, v[1]);
insert_cube_vertices (box, visit[(i + 5) % 6], 2, v[2], v[1]);
insert_cube_vertices (box, visit[i], 1, v[0]);
insert_cube_vertices (box, visit[(i + 1) % 6], 2, v[1], v[0]);
insert_cube_vertices (box, visit[(i + 2) % 6], 1, v[1]);
} else {
// opposing vertices
vec3_t v[2];
find_cube_vertex (visit[i].face, visit[(i + 1) % 6].face,
visit[(i + 2) % 6].face, v[0]);
find_cube_vertex (visit[(i + 3) % 6].face,
visit[(i + 4) % 6].face,
visit[(i + 5) % 6].face, v[1]);
insert_cube_vertices (box, visit[i], 1, v[0]);
insert_cube_vertices (box, visit[(i + 1) % 6], 1, v[0]);
insert_cube_vertices (box, visit[(i + 3) % 6], 1, v[1]);
insert_cube_vertices (box, visit[(i + 4) % 6], 1, v[1]);
insert_cube_vertices (box, visit[(i + 2) % 6], 1, v[1]);
insert_cube_vertices (box, visit[(i + 5) % 6], 1, v[0]);
}
break;
case 7:
for (i = 0; i < 6; i++) {
// don't need to check the last point
if (visit[(i + 2) % 6].face == visit[(i + 4) % 6].face
&& visit[(i + 4) % 6].face == visit[(i + 6) % 6].face)
break;
}
{
vec3_t v;
find_cube_vertex (visit[i].face, visit[(i + 1) % 6].face,
visit[(i + 2) % 6].face, v);
insert_cube_vertices (box, visit[i], 1, v);
insert_cube_vertices (box, visit[(i + 1) % 7], 1, v);
insert_cube_vertices (box, visit[(i + 6) % 7], 1, v);
}
break;
}
}
/*
render_box
draws all faces of the cube with 3 or more vertices.
*/
static void
render_box (struct box_def *box)
{
int i, j;
for (i = 0; i < 6; i++) {
if (box->face[i].poly.numverts <= 2)
continue;
glBindTexture (GL_TEXTURE_2D, box->face[i].tex);
glBegin (GL_POLYGON);
for (j = 0; j < box->face[i].poly.numverts; j++) {
glTexCoord2fv (box->face[i].poly.verts[j] + 3);
glVertex3fv (box->face[i].poly.verts[j]);
}
glEnd ();
}
}
void
R_DrawSkyBoxPoly (glpoly_t *poly)
{
int i;
struct box_def box;
/* projected vertex and face of the previous sky poly vertex */
vec3_t last_v;
int prev_face;
/* projected vertex and face of the current sky poly vertex */
vec3_t v;
int face;
memset (&box, 0, sizeof (box));
for (i = 0; i < 6; i++) {
box.face[i].tex = SKY_TEX + skytex_offs[i];
}
if (poly->numverts >= 32) {
Sys_Error ("too many verts!");
}
VectorSubtract (poly->verts[poly->numverts - 1], r_refdef.vieworg, last_v);
prev_face = determine_face (last_v);
box.visited_faces[0].face = prev_face;
box.face_count = 1;
for (i = 0; i < poly->numverts; i++) {
VectorSubtract (poly->verts[i], r_refdef.vieworg, v);
face = determine_face (v);
if (face != prev_face) {
if ((face_axis[face]) == (face_axis[prev_face])) {
int x_face;
vec3_t x;
VectorAdd (v, last_v, x);
VectorScale (x, 0.5, x);
x_face = determine_face (x);
cross_cube_edge (&box, prev_face, last_v, x_face, x);
cross_cube_edge (&box, x_face, x, face, v);
} else {
cross_cube_edge (&box, prev_face, last_v, face, v);
}
}
add_vertex (&box, face, v);
VectorCopy (v, last_v);
prev_face = face;
}
process_corners (&box);
render_box (&box);
}
void
R_DrawSkyDomePoly (glpoly_t *poly)
{
int i;
glBegin (GL_POLYGON);
for (i = 0; i < poly->numverts; i++) {
glVertex3fv (poly->verts[i]);
}
glEnd ();
}
void
R_DrawSkyChain (msurface_t *sky_chain)
{
msurface_t *sc = sky_chain;
float l = 1 / (256 * brightness->value);
glColor3f (lighthalf_v[0] * l, lighthalf_v[1] * l, lighthalf_v[2] * l);
if (skyloaded) {
glDepthRange (gldepthmax, gldepthmax);
while (sc) {
glpoly_t *p = sc->polys;
while (p) {
R_DrawSkyBoxPoly (p);
p = p->next;
}
sc = sc->texturechain;
}
glDepthRange (gldepthmin, gldepthmax);
} else {
glDisable (GL_BLEND);
glDisable (GL_TEXTURE_2D);
glColor3f (0, 0, 0);
while (sc) {
glpoly_t *p = sc->polys;
while (p) {
R_DrawSkyDomePoly (p);
p = p->next;
}
sc = sc->texturechain;
}
glEnable (GL_TEXTURE_2D);
glEnable (GL_BLEND);
}
#if 0
// seems to work, but this is the wrong place to do it.
glColor4f (1,1,1,0);
sc = sky_chain;
while (sc) {
glpoly_t *p = sc->polys;
while (p) {
int i;
glBegin (GL_POLYGON);
for (i = 0; i < p->numverts; i++) {
glVertex3fv (p->verts[i]);
}
glEnd ();
p = p->next;
}
sc = sc->texturechain;
}
#endif
glColor3ubv (lighthalf_v);
#if 0
glDisable (GL_TEXTURE_2D);
sc = sky_chain;
glColor3f (1, 1, 1);
while (sc) {
glpoly_t *p = sc->polys;
while (p) {
int i;
glBegin (GL_LINE_LOOP);
for (i = 0; i < p->numverts; i++) {
glVertex3fv (p->verts[i]);
}
glEnd ();
p = p->next;
}
sc = sc->texturechain;
}
sc = sky_chain;
glColor3f (0, 1, 0);
glBegin (GL_POINTS);
while (sc) {
glpoly_t *p = sc->polys;
while (p) {
int i;
vec3_t x, c = { 0, 0, 0 };
for (i = 0; i < p->numverts; i++) {
VectorSubtract (p->verts[i], r_refdef.vieworg, x);
VectorAdd (x, c, c);
}
VectorScale (c, 1.0 / p->numverts, c);
VectorAdd (c, r_refdef.vieworg, c);
glVertex3fv (c);
p = p->next;
}
sc = sc->texturechain;
}
glEnd ();
if (skyloaded) {
int i, j;
glColor3f (1, 0, 0);
for (i = 0; i < 6; i++) {
vec3_t v;
glBegin (GL_LINE_LOOP);
for (j = 0; j < 4; j++) {
memcpy (v, &skyvec[i][j][2], sizeof (v));
VectorAdd (v, r_refdef.vieworg, v);
glVertex3fv (v);
}
glEnd ();
}
}
glColor3ubv (lighthalf_v);
glEnable (GL_TEXTURE_2D);
#endif
}