void glopEnd(GLContext * c, GLParam * param)
{
(void) param;
gl_assert(c->in_begin == 1);
if (c->begin_type == GL_LINE_LOOP) {
if (c->vertex_cnt >= 3) {
gl_draw_line(c, &c->vertex[0], &c->vertex[2]);
}
} else if (c->begin_type == GL_POLYGON) {
int i = c->vertex_cnt;
while (i >= 3) {
i--;
gl_draw_triangle(c, &c->vertex[i], &c->vertex[0], &c->vertex[i - 1]);
}
}
c->in_begin = 0;
}
static void gl_draw_triangle_clip(GLContext *c, GLVertex *p0, GLVertex *p1, GLVertex *p2, int clip_bit) {
int co, c_and, co1, cc[3], edge_flag_tmp, clip_mask;
GLVertex tmp1, tmp2, *q[3];
float tt;
cc[0] = p0->clip_code;
cc[1] = p1->clip_code;
cc[2] = p2->clip_code;
co = cc[0] | cc[1] | cc[2];
if (co == 0) {
gl_draw_triangle(c, p0, p1, p2);
} else {
c_and = cc[0] & cc[1] & cc[2];
// the triangle is completely outside
if (c_and != 0)
return;
// find the next direction to clip
while (clip_bit < 6 && (co & (1 << clip_bit)) == 0) {
clip_bit++;
}
// this test can be true only in case of rounding errors
if (clip_bit == 6) {
#if 0
printf("Error:\n");
printf("%f %f %f %f\n", p0->pc.X, p0->pc.Y, p0->pc.Z, p0->pc.W);
printf("%f %f %f %f\n", p1->pc.X, p1->pc.Y, p1->pc.Z, p1->pc.W);
printf("%f %f %f %f\n", p2->pc.X, p2->pc.Y, p2->pc.Z, p2->pc.W);
#endif
return;
}
clip_mask = 1 << clip_bit;
co1 = (cc[0] ^ cc[1] ^ cc[2]) & clip_mask;
if (co1) {
// one point outside
if (cc[0] & clip_mask) {
q[0] = p0; q[1] = p1; q[2] = p2;
} else if (cc[1] & clip_mask) {
q[0] = p1; q[1] = p2; q[2] = p0;
} else {
q[0] = p2; q[1] = p0; q[2] = p1;
}
tt = clip_proc[clip_bit](&tmp1.pc, &q[0]->pc, &q[1]->pc);
updateTmp(c, &tmp1, q[0], q[1], tt);
tt = clip_proc[clip_bit](&tmp2.pc, &q[0]->pc, &q[2]->pc);
updateTmp(c, &tmp2, q[0], q[2], tt);
tmp1.edge_flag = q[0]->edge_flag;
edge_flag_tmp = q[2]->edge_flag;
q[2]->edge_flag = 0;
gl_draw_triangle_clip(c, &tmp1, q[1], q[2], clip_bit + 1);
tmp2.edge_flag = 1;
tmp1.edge_flag = 0;
q[2]->edge_flag = edge_flag_tmp;
gl_draw_triangle_clip(c, &tmp2, &tmp1, q[2], clip_bit + 1);
} else {
// two points outside
if ((cc[0] & clip_mask) == 0) {
q[0] = p0; q[1] = p1; q[2] = p2;
} else if ((cc[1] & clip_mask) == 0) {
q[0] = p1; q[1] = p2; q[2] = p0;
} else {
q[0] = p2; q[1] = p0; q[2] = p1;
}
tt = clip_proc[clip_bit](&tmp1.pc, &q[0]->pc, &q[1]->pc);
updateTmp(c, &tmp1, q[0], q[1], tt);
tt = clip_proc[clip_bit](&tmp2.pc, &q[0]->pc, &q[2]->pc);
updateTmp(c, &tmp2, q[0], q[2], tt);
tmp1.edge_flag = 1;
tmp2.edge_flag = q[2]->edge_flag;
gl_draw_triangle_clip(c, q[0], &tmp1, &tmp2, clip_bit + 1);
}
}
}
void glopVertex(GLContext * c, GLParam * p)
{
GLVertex *v;
int n, i, cnt;
gl_assert(c->in_begin != 0);
n = c->vertex_n;
cnt = c->vertex_cnt;
cnt++;
c->vertex_cnt = cnt;
/* quick fix to avoid crashes on large polygons */
if (n >= c->vertex_max) {
GLVertex *newarray;
c->vertex_max <<= 1; /* just double size */
newarray = gl_malloc(sizeof(GLVertex) * c->vertex_max);
if (!newarray) {
gl_fatal_error("unable to allocate GLVertex array.\n");
}
memcpy(newarray, c->vertex, n * sizeof(GLVertex));
gl_free(c->vertex);
c->vertex = newarray;
}
/* new vertex entry */
v = &c->vertex[n];
n++;
v->coord.X = p[1].f;
v->coord.Y = p[2].f;
v->coord.Z = p[3].f;
v->coord.W = p[4].f;
gl_vertex_transform(c, v);
/* color */
if (c->lighting_enabled) {
gl_shade_vertex(c, v);
} else {
v->color = c->current_color;
}
/* tex coords */
if (c->texture_2d_enabled) {
if (c->apply_texture_matrix) {
gl_M4_MulV4(&v->tex_coord, c->matrix_stack_ptr[2], &c->current_tex_coord);
} else {
v->tex_coord = c->current_tex_coord;
}
}
/* precompute the mapping to the viewport */
if (v->clip_code == 0)
gl_transform_to_viewport(c, v);
/* edge flag */
v->edge_flag = c->current_edge_flag;
switch (c->begin_type) {
case GL_POINTS:
gl_draw_point(c, &c->vertex[0]);
n = 0;
break;
case GL_LINES:
if (n == 2) {
gl_draw_line(c, &c->vertex[0], &c->vertex[1]);
n = 0;
}
break;
case GL_LINE_STRIP:
case GL_LINE_LOOP:
if (n == 1) {
c->vertex[2] = c->vertex[0];
} else if (n == 2) {
gl_draw_line(c, &c->vertex[0], &c->vertex[1]);
c->vertex[0] = c->vertex[1];
n = 1;
}
break;
case GL_TRIANGLES:
if (n == 3) {
gl_draw_triangle(c, &c->vertex[0], &c->vertex[1], &c->vertex[2]);
n = 0;
}
break;
case GL_TRIANGLE_STRIP:
if (cnt >= 3) {
if (n == 3)
n = 0;
/* needed to respect triangle orientation */
switch(cnt & 1) {
case 0:
gl_draw_triangle(c,&c->vertex[2],&c->vertex[1],&c->vertex[0]);
break;
default:
case 1:
gl_draw_triangle(c,&c->vertex[0],&c->vertex[1],&c->vertex[2]);
break;
}
}
break;
case GL_TRIANGLE_FAN:
if (n == 3) {
gl_draw_triangle(c, &c->vertex[0], &c->vertex[1], &c->vertex[2]);
c->vertex[1] = c->vertex[2];
n = 2;
}
break;
case GL_QUADS:
if (n == 4) {
c->vertex[2].edge_flag = 0;
gl_draw_triangle(c, &c->vertex[0], &c->vertex[1], &c->vertex[2]);
c->vertex[2].edge_flag = 1;
c->vertex[0].edge_flag = 0;
gl_draw_triangle(c, &c->vertex[0], &c->vertex[2], &c->vertex[3]);
n = 0;
}
break;
case GL_QUAD_STRIP:
if (n == 4) {
gl_draw_triangle(c, &c->vertex[0], &c->vertex[1], &c->vertex[2]);
gl_draw_triangle(c, &c->vertex[1], &c->vertex[3], &c->vertex[2]);
for (i = 0; i < 2; i++)
c->vertex[i] = c->vertex[i + 2];
n = 2;
}
break;
case GL_POLYGON:
break;
default:
gl_fatal_error("glBegin: type %x not handled\n", c->begin_type);
}
c->vertex_n = n;
}