void gl_draw_line(GLContext *c, GLVertex *p1, GLVertex *p2) {
float dx, dy, dz, dw, x1, y1, z1, w1;
float tmin, tmax;
GLVertex q1, q2;
int cc1, cc2;
cc1 = p1->clip_code;
cc2 = p2->clip_code;
if ((cc1 | cc2) == 0) {
if (c->render_mode == TGL_SELECT) {
gl_add_select1(c, p1->zp.z, p2->zp.z, p2->zp.z);
} else {
if (c->depth_test)
c->fb->fillLineZ(&p1->zp, &p2->zp);
else
c->fb->fillLine(&p1->zp, &p2->zp);
}
} else if ((cc1 & cc2) != 0) {
return;
} else {
dx = p2->pc.X - p1->pc.X;
dy = p2->pc.Y - p1->pc.Y;
dz = p2->pc.Z - p1->pc.Z;
dw = p2->pc.W - p1->pc.W;
x1 = p1->pc.X;
y1 = p1->pc.Y;
z1 = p1->pc.Z;
w1 = p1->pc.W;
tmin = 0;
tmax = 1;
if (ClipLine1(dx + dw, -x1 - w1, &tmin, &tmax) &&
ClipLine1(-dx + dw, x1 - w1, &tmin, &tmax) &&
ClipLine1(dy + dw, -y1 - w1, &tmin, &tmax) &&
ClipLine1(-dy + dw, y1 - w1, &tmin, &tmax) &&
ClipLine1(dz + dw, -z1 - w1, &tmin, &tmax) &&
ClipLine1(-dz + dw, z1 - w1, &tmin, &tmax)) {
interpolate(c, &q1, p1, p2, tmin);
interpolate(c, &q2, p1, p2, tmax);
gl_transform_to_viewport(c, &q1);
gl_transform_to_viewport(c, &q2);
if (c->depth_test)
c->fb->fillLineZ(&q1.zp, &q2.zp);
else
c->fb->fillLine(&q1.zp, &q2.zp);
}
}
}
static inline void updateTmp(GLContext *c, GLVertex *q, GLVertex *p0, GLVertex *p1, float t) {
interpolate_color(c, q, p0, p1, t);
if (c->texture_2d_enabled) {
// NOTE: This could be implemented with operator overloading,
// but i'm not 100% sure that we can completely disregard Z and W components so I'm leaving it like this for now.
q->tex_coord.X = (p0->tex_coord.X + (p1->tex_coord.X - p0->tex_coord.X) * t);
q->tex_coord.Y = (p0->tex_coord.Y + (p1->tex_coord.Y - p0->tex_coord.Y) * t);
}
q->clip_code = gl_clipcode(q->pc.X, q->pc.Y, q->pc.Z, q->pc.W);
if (q->clip_code == 0)
gl_transform_to_viewport(c, q);
}
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;
}
