Split vertex clipping code out into vertex-clipping.c

dev
Sam Spilsbury 11 years ago committed by Kristian Høgsberg
parent 4a4704a7d0
commit 619859ce90
  1. 4
      src/Makefile.am
  2. 292
      src/gl-renderer.c
  3. 317
      src/vertex-clipping.c
  4. 65
      src/vertex-clipping.h

@ -52,7 +52,9 @@ weston_SOURCES = \
if ENABLE_EGL if ENABLE_EGL
weston_SOURCES += \ weston_SOURCES += \
gl-renderer.c gl-renderer.c \
vertex-clipping.c \
vertex-clipping.h
endif endif
git-version.h : .FORCE git-version.h : .FORCE

@ -33,6 +33,7 @@
#include <linux/input.h> #include <linux/input.h>
#include "gl-renderer.h" #include "gl-renderer.h"
#include "vertex-clipping.h"
#include <EGL/eglext.h> #include <EGL/eglext.h>
#include "weston-egl-ext.h" #include "weston-egl-ext.h"
@ -179,270 +180,8 @@ gl_renderer_print_egl_error_state(void)
egl_error_string(code), (long)code); egl_error_string(code), (long)code);
} }
struct polygon8 {
GLfloat x[8];
GLfloat y[8];
int n;
};
struct clip_context {
struct {
GLfloat x;
GLfloat y;
} prev;
struct {
GLfloat x1, y1;
GLfloat x2, y2;
} clip;
struct {
GLfloat *x;
GLfloat *y;
} vertices;
};
static GLfloat
float_difference(GLfloat a, GLfloat b)
{
/* http://www.altdevblogaday.com/2012/02/22/comparing-floating-point-numbers-2012-edition/ */
static const GLfloat max_diff = 4.0f * FLT_MIN;
static const GLfloat max_rel_diff = 4.0e-5;
GLfloat diff = a - b;
GLfloat adiff = fabsf(diff);
if (adiff <= max_diff)
return 0.0f;
a = fabsf(a);
b = fabsf(b);
if (adiff <= (a > b ? a : b) * max_rel_diff)
return 0.0f;
return diff;
}
/* A line segment (p1x, p1y)-(p2x, p2y) intersects the line x = x_arg.
* Compute the y coordinate of the intersection.
*/
static GLfloat
clip_intersect_y(GLfloat p1x, GLfloat p1y, GLfloat p2x, GLfloat p2y,
GLfloat x_arg)
{
GLfloat a;
GLfloat diff = float_difference(p1x, p2x);
/* Practically vertical line segment, yet the end points have already
* been determined to be on different sides of the line. Therefore
* the line segment is part of the line and intersects everywhere.
* Return the end point, so we use the whole line segment.
*/
if (diff == 0.0f)
return p2y;
a = (x_arg - p2x) / diff;
return p2y + (p1y - p2y) * a;
}
/* A line segment (p1x, p1y)-(p2x, p2y) intersects the line y = y_arg.
* Compute the x coordinate of the intersection.
*/
static GLfloat
clip_intersect_x(GLfloat p1x, GLfloat p1y, GLfloat p2x, GLfloat p2y,
GLfloat y_arg)
{
GLfloat a;
GLfloat diff = float_difference(p1y, p2y);
/* Practically horizontal line segment, yet the end points have already
* been determined to be on different sides of the line. Therefore
* the line segment is part of the line and intersects everywhere.
* Return the end point, so we use the whole line segment.
*/
if (diff == 0.0f)
return p2x;
a = (y_arg - p2y) / diff;
return p2x + (p1x - p2x) * a;
}
enum path_transition {
PATH_TRANSITION_OUT_TO_OUT = 0,
PATH_TRANSITION_OUT_TO_IN = 1,
PATH_TRANSITION_IN_TO_OUT = 2,
PATH_TRANSITION_IN_TO_IN = 3,
};
static void
clip_append_vertex(struct clip_context *ctx, GLfloat x, GLfloat y)
{
*ctx->vertices.x++ = x;
*ctx->vertices.y++ = y;
}
static enum path_transition
path_transition_left_edge(struct clip_context *ctx, GLfloat x, GLfloat y)
{
return ((ctx->prev.x >= ctx->clip.x1) << 1) | (x >= ctx->clip.x1);
}
static enum path_transition
path_transition_right_edge(struct clip_context *ctx, GLfloat x, GLfloat y)
{
return ((ctx->prev.x < ctx->clip.x2) << 1) | (x < ctx->clip.x2);
}
static enum path_transition
path_transition_top_edge(struct clip_context *ctx, GLfloat x, GLfloat y)
{
return ((ctx->prev.y >= ctx->clip.y1) << 1) | (y >= ctx->clip.y1);
}
static enum path_transition
path_transition_bottom_edge(struct clip_context *ctx, GLfloat x, GLfloat y)
{
return ((ctx->prev.y < ctx->clip.y2) << 1) | (y < ctx->clip.y2);
}
static void
clip_polygon_leftright(struct clip_context *ctx,
enum path_transition transition,
GLfloat x, GLfloat y, GLfloat clip_x)
{
GLfloat yi;
switch (transition) {
case PATH_TRANSITION_IN_TO_IN:
clip_append_vertex(ctx, x, y);
break;
case PATH_TRANSITION_IN_TO_OUT:
yi = clip_intersect_y(ctx->prev.x, ctx->prev.y, x, y, clip_x);
clip_append_vertex(ctx, clip_x, yi);
break;
case PATH_TRANSITION_OUT_TO_IN:
yi = clip_intersect_y(ctx->prev.x, ctx->prev.y, x, y, clip_x);
clip_append_vertex(ctx, clip_x, yi);
clip_append_vertex(ctx, x, y);
break;
case PATH_TRANSITION_OUT_TO_OUT:
/* nothing */
break;
default:
assert(0 && "bad enum path_transition");
}
ctx->prev.x = x;
ctx->prev.y = y;
}
static void
clip_polygon_topbottom(struct clip_context *ctx,
enum path_transition transition,
GLfloat x, GLfloat y, GLfloat clip_y)
{
GLfloat xi;
switch (transition) {
case PATH_TRANSITION_IN_TO_IN:
clip_append_vertex(ctx, x, y);
break;
case PATH_TRANSITION_IN_TO_OUT:
xi = clip_intersect_x(ctx->prev.x, ctx->prev.y, x, y, clip_y);
clip_append_vertex(ctx, xi, clip_y);
break;
case PATH_TRANSITION_OUT_TO_IN:
xi = clip_intersect_x(ctx->prev.x, ctx->prev.y, x, y, clip_y);
clip_append_vertex(ctx, xi, clip_y);
clip_append_vertex(ctx, x, y);
break;
case PATH_TRANSITION_OUT_TO_OUT:
/* nothing */
break;
default:
assert(0 && "bad enum path_transition");
}
ctx->prev.x = x;
ctx->prev.y = y;
}
static void
clip_context_prepare(struct clip_context *ctx, const struct polygon8 *src,
GLfloat *dst_x, GLfloat *dst_y)
{
ctx->prev.x = src->x[src->n - 1];
ctx->prev.y = src->y[src->n - 1];
ctx->vertices.x = dst_x;
ctx->vertices.y = dst_y;
}
static int
clip_polygon_left(struct clip_context *ctx, const struct polygon8 *src,
GLfloat *dst_x, GLfloat *dst_y)
{
enum path_transition trans;
int i;
clip_context_prepare(ctx, src, dst_x, dst_y);
for (i = 0; i < src->n; i++) {
trans = path_transition_left_edge(ctx, src->x[i], src->y[i]);
clip_polygon_leftright(ctx, trans, src->x[i], src->y[i],
ctx->clip.x1);
}
return ctx->vertices.x - dst_x;
}
static int
clip_polygon_right(struct clip_context *ctx, const struct polygon8 *src,
GLfloat *dst_x, GLfloat *dst_y)
{
enum path_transition trans;
int i;
clip_context_prepare(ctx, src, dst_x, dst_y);
for (i = 0; i < src->n; i++) {
trans = path_transition_right_edge(ctx, src->x[i], src->y[i]);
clip_polygon_leftright(ctx, trans, src->x[i], src->y[i],
ctx->clip.x2);
}
return ctx->vertices.x - dst_x;
}
static int
clip_polygon_top(struct clip_context *ctx, const struct polygon8 *src,
GLfloat *dst_x, GLfloat *dst_y)
{
enum path_transition trans;
int i;
clip_context_prepare(ctx, src, dst_x, dst_y);
for (i = 0; i < src->n; i++) {
trans = path_transition_top_edge(ctx, src->x[i], src->y[i]);
clip_polygon_topbottom(ctx, trans, src->x[i], src->y[i],
ctx->clip.y1);
}
return ctx->vertices.x - dst_x;
}
static int
clip_polygon_bottom(struct clip_context *ctx, const struct polygon8 *src,
GLfloat *dst_x, GLfloat *dst_y)
{
enum path_transition trans;
int i;
clip_context_prepare(ctx, src, dst_x, dst_y);
for (i = 0; i < src->n; i++) {
trans = path_transition_bottom_edge(ctx, src->x[i], src->y[i]);
clip_polygon_topbottom(ctx, trans, src->x[i], src->y[i],
ctx->clip.y2);
}
return ctx->vertices.x - dst_x;
}
#define max(a, b) (((a) > (b)) ? (a) : (b)) #define max(a, b) (((a) > (b)) ? (a) : (b))
#define min(a, b) (((a) > (b)) ? (b) : (a)) #define min(a, b) (((a) > (b)) ? (b) : (a))
#define clip(x, a, b) min(max(x, a), b)
/* /*
* Compute the boundary vertices of the intersection of the global coordinate * Compute the boundary vertices of the intersection of the global coordinate
@ -457,7 +196,7 @@ static int
calculate_edges(struct weston_surface *es, pixman_box32_t *rect, calculate_edges(struct weston_surface *es, pixman_box32_t *rect,
pixman_box32_t *surf_rect, GLfloat *ex, GLfloat *ey) pixman_box32_t *surf_rect, GLfloat *ex, GLfloat *ey)
{ {
struct polygon8 polygon;
struct clip_context ctx; struct clip_context ctx;
int i, n; int i, n;
GLfloat min_x, max_x, min_y, max_y; GLfloat min_x, max_x, min_y, max_y;
@ -500,11 +239,7 @@ calculate_edges(struct weston_surface *es, pixman_box32_t *rect,
* vertices to the clip rect bounds: * vertices to the clip rect bounds:
*/ */
if (!es->transform.enabled) { if (!es->transform.enabled) {
for (i = 0; i < surf.n; i++) { return clip_simple(&ctx, &surf, ex, ey);
ex[i] = clip(surf.x[i], ctx.clip.x1, ctx.clip.x2);
ey[i] = clip(surf.y[i], ctx.clip.y1, ctx.clip.y2);
}
return surf.n;
} }
/* Transformed case: use a general polygon clipping algorithm to /* Transformed case: use a general polygon clipping algorithm to
@ -513,26 +248,7 @@ calculate_edges(struct weston_surface *es, pixman_box32_t *rect,
* http://www.codeguru.com/cpp/misc/misc/graphics/article.php/c8965/Polygon-Clipping.htm * http://www.codeguru.com/cpp/misc/misc/graphics/article.php/c8965/Polygon-Clipping.htm
* but without looking at any of that code. * but without looking at any of that code.
*/ */
polygon.n = clip_polygon_left(&ctx, &surf, polygon.x, polygon.y); n = clip_transformed(&ctx, &surf, ex, ey);
surf.n = clip_polygon_right(&ctx, &polygon, surf.x, surf.y);
polygon.n = clip_polygon_top(&ctx, &surf, polygon.x, polygon.y);
surf.n = clip_polygon_bottom(&ctx, &polygon, surf.x, surf.y);
/* Get rid of duplicate vertices */
ex[0] = surf.x[0];
ey[0] = surf.y[0];
n = 1;
for (i = 1; i < surf.n; i++) {
if (float_difference(ex[n - 1], surf.x[i]) == 0.0f &&
float_difference(ey[n - 1], surf.y[i]) == 0.0f)
continue;
ex[n] = surf.x[i];
ey[n] = surf.y[i];
n++;
}
if (float_difference(ex[n - 1], surf.x[0]) == 0.0f &&
float_difference(ey[n - 1], surf.y[0]) == 0.0f)
n--;
if (n < 3) if (n < 3)
return 0; return 0;

@ -0,0 +1,317 @@
/*
* Copyright © 2012 Intel Corporation
*
* Permission to use, copy, modify, distribute, and sell this software and
* its documentation for any purpose is hereby granted without fee, provided
* that the above copyright notice appear in all copies and that both that
* copyright notice and this permission notice appear in supporting
* documentation, and that the name of the copyright holders not be used in
* advertising or publicity pertaining to distribution of the software
* without specific, written prior permission. The copyright holders make
* no representations about the suitability of this software for any
* purpose. It is provided "as is" without express or implied warranty.
*
* THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS
* SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS, IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY
* SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
* RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF
* CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <assert.h>
#include <float.h>
#include <math.h>
#include <GLES2/gl2.h>
#include "vertex-clipping.h"
GLfloat
float_difference(GLfloat a, GLfloat b)
{
/* http://www.altdevblogaday.com/2012/02/22/comparing-floating-point-numbers-2012-edition/ */
static const GLfloat max_diff = 4.0f * FLT_MIN;
static const GLfloat max_rel_diff = 4.0e-5;
GLfloat diff = a - b;
GLfloat adiff = fabsf(diff);
if (adiff <= max_diff)
return 0.0f;
a = fabsf(a);
b = fabsf(b);
if (adiff <= (a > b ? a : b) * max_rel_diff)
return 0.0f;
return diff;
}
/* A line segment (p1x, p1y)-(p2x, p2y) intersects the line x = x_arg.
* Compute the y coordinate of the intersection.
*/
static GLfloat
clip_intersect_y(GLfloat p1x, GLfloat p1y, GLfloat p2x, GLfloat p2y,
GLfloat x_arg)
{
GLfloat a;
GLfloat diff = float_difference(p1x, p2x);
/* Practically vertical line segment, yet the end points have already
* been determined to be on different sides of the line. Therefore
* the line segment is part of the line and intersects everywhere.
* Return the end point, so we use the whole line segment.
*/
if (diff == 0.0f)
return p2y;
a = (x_arg - p2x) / diff;
return p2y + (p1y - p2y) * a;
}
/* A line segment (p1x, p1y)-(p2x, p2y) intersects the line y = y_arg.
* Compute the x coordinate of the intersection.
*/
static GLfloat
clip_intersect_x(GLfloat p1x, GLfloat p1y, GLfloat p2x, GLfloat p2y,
GLfloat y_arg)
{
GLfloat a;
GLfloat diff = float_difference(p1y, p2y);
/* Practically horizontal line segment, yet the end points have already
* been determined to be on different sides of the line. Therefore
* the line segment is part of the line and intersects everywhere.
* Return the end point, so we use the whole line segment.
*/
if (diff == 0.0f)
return p2x;
a = (y_arg - p2y) / diff;
return p2x + (p1x - p2x) * a;
}
enum path_transition {
PATH_TRANSITION_OUT_TO_OUT = 0,
PATH_TRANSITION_OUT_TO_IN = 1,
PATH_TRANSITION_IN_TO_OUT = 2,
PATH_TRANSITION_IN_TO_IN = 3,
};
static void
clip_append_vertex(struct clip_context *ctx, GLfloat x, GLfloat y)
{
*ctx->vertices.x++ = x;
*ctx->vertices.y++ = y;
}
static enum path_transition
path_transition_left_edge(struct clip_context *ctx, GLfloat x, GLfloat y)
{
return ((ctx->prev.x >= ctx->clip.x1) << 1) | (x >= ctx->clip.x1);
}
static enum path_transition
path_transition_right_edge(struct clip_context *ctx, GLfloat x, GLfloat y)
{
return ((ctx->prev.x < ctx->clip.x2) << 1) | (x < ctx->clip.x2);
}
static enum path_transition
path_transition_top_edge(struct clip_context *ctx, GLfloat x, GLfloat y)
{
return ((ctx->prev.y >= ctx->clip.y1) << 1) | (y >= ctx->clip.y1);
}
static enum path_transition
path_transition_bottom_edge(struct clip_context *ctx, GLfloat x, GLfloat y)
{
return ((ctx->prev.y < ctx->clip.y2) << 1) | (y < ctx->clip.y2);
}
static void
clip_polygon_leftright(struct clip_context *ctx,
enum path_transition transition,
GLfloat x, GLfloat y, GLfloat clip_x)
{
GLfloat yi;
switch (transition) {
case PATH_TRANSITION_IN_TO_IN:
clip_append_vertex(ctx, x, y);
break;
case PATH_TRANSITION_IN_TO_OUT:
yi = clip_intersect_y(ctx->prev.x, ctx->prev.y, x, y, clip_x);
clip_append_vertex(ctx, clip_x, yi);
break;
case PATH_TRANSITION_OUT_TO_IN:
yi = clip_intersect_y(ctx->prev.x, ctx->prev.y, x, y, clip_x);
clip_append_vertex(ctx, clip_x, yi);
clip_append_vertex(ctx, x, y);
break;
case PATH_TRANSITION_OUT_TO_OUT:
/* nothing */
break;
default:
assert(0 && "bad enum path_transition");
}
ctx->prev.x = x;
ctx->prev.y = y;
}
static void
clip_polygon_topbottom(struct clip_context *ctx,
enum path_transition transition,
GLfloat x, GLfloat y, GLfloat clip_y)
{
GLfloat xi;
switch (transition) {
case PATH_TRANSITION_IN_TO_IN:
clip_append_vertex(ctx, x, y);
break;
case PATH_TRANSITION_IN_TO_OUT:
xi = clip_intersect_x(ctx->prev.x, ctx->prev.y, x, y, clip_y);
clip_append_vertex(ctx, xi, clip_y);
break;
case PATH_TRANSITION_OUT_TO_IN:
xi = clip_intersect_x(ctx->prev.x, ctx->prev.y, x, y, clip_y);
clip_append_vertex(ctx, xi, clip_y);
clip_append_vertex(ctx, x, y);
break;
case PATH_TRANSITION_OUT_TO_OUT:
/* nothing */
break;
default:
assert(0 && "bad enum path_transition");
}
ctx->prev.x = x;
ctx->prev.y = y;
}
static void
clip_context_prepare(struct clip_context *ctx, const struct polygon8 *src,
GLfloat *dst_x, GLfloat *dst_y)
{
ctx->prev.x = src->x[src->n - 1];
ctx->prev.y = src->y[src->n - 1];
ctx->vertices.x = dst_x;
ctx->vertices.y = dst_y;
}
static int
clip_polygon_left(struct clip_context *ctx, const struct polygon8 *src,
GLfloat *dst_x, GLfloat *dst_y)
{
enum path_transition trans;
int i;
clip_context_prepare(ctx, src, dst_x, dst_y);
for (i = 0; i < src->n; i++) {
trans = path_transition_left_edge(ctx, src->x[i], src->y[i]);
clip_polygon_leftright(ctx, trans, src->x[i], src->y[i],
ctx->clip.x1);
}
return ctx->vertices.x - dst_x;
}
static int
clip_polygon_right(struct clip_context *ctx, const struct polygon8 *src,
GLfloat *dst_x, GLfloat *dst_y)
{
enum path_transition trans;
int i;
clip_context_prepare(ctx, src, dst_x, dst_y);
for (i = 0; i < src->n; i++) {
trans = path_transition_right_edge(ctx, src->x[i], src->y[i]);
clip_polygon_leftright(ctx, trans, src->x[i], src->y[i],
ctx->clip.x2);
}
return ctx->vertices.x - dst_x;
}
static int
clip_polygon_top(struct clip_context *ctx, const struct polygon8 *src,
GLfloat *dst_x, GLfloat *dst_y)
{
enum path_transition trans;
int i;
clip_context_prepare(ctx, src, dst_x, dst_y);
for (i = 0; i < src->n; i++) {
trans = path_transition_top_edge(ctx, src->x[i], src->y[i]);
clip_polygon_topbottom(ctx, trans, src->x[i], src->y[i],
ctx->clip.y1);
}
return ctx->vertices.x - dst_x;
}
static int
clip_polygon_bottom(struct clip_context *ctx, const struct polygon8 *src,
GLfloat *dst_x, GLfloat *dst_y)
{
enum path_transition trans;
int i;
clip_context_prepare(ctx, src, dst_x, dst_y);
for (i = 0; i < src->n; i++) {
trans = path_transition_bottom_edge(ctx, src->x[i], src->y[i]);
clip_polygon_topbottom(ctx, trans, src->x[i], src->y[i],
ctx->clip.y2);
}
return ctx->vertices.x - dst_x;
}
#define max(a, b) (((a) > (b)) ? (a) : (b))
#define min(a, b) (((a) > (b)) ? (b) : (a))
#define clip(x, a, b) min(max(x, a), b)
int
clip_simple(struct clip_context *ctx,
struct polygon8 *surf,
GLfloat *ex,
GLfloat *ey)
{
int i;
for (i = 0; i < surf->n; i++) {
ex[i] = clip(surf->x[i], ctx->clip.x1, ctx->clip.x2);
ey[i] = clip(surf->y[i], ctx->clip.y1, ctx->clip.y2);
}
return surf->n;
}
int
clip_transformed(struct clip_context *ctx,
struct polygon8 *surf,
GLfloat *ex,
GLfloat *ey)
{
struct polygon8 polygon;
int i, n;
polygon.n = clip_polygon_left(ctx, surf, polygon.x, polygon.y);
surf->n = clip_polygon_right(ctx, &polygon, surf->x, surf->y);
polygon.n = clip_polygon_top(ctx, surf, polygon.x, polygon.y);
surf->n = clip_polygon_bottom(ctx, &polygon, surf->x, surf->y);
/* Get rid of duplicate vertices */
ex[0] = surf->x[0];
ey[0] = surf->y[0];
n = 1;
for (i = 1; i < surf->n; i++) {
if (float_difference(ex[n - 1], surf->x[i]) == 0.0f &&
float_difference(ey[n - 1], surf->y[i]) == 0.0f)
continue;
ex[n] = surf->x[i];
ey[n] = surf->y[i];
n++;
}
if (float_difference(ex[n - 1], surf->x[0]) == 0.0f &&
float_difference(ey[n - 1], surf->y[0]) == 0.0f)
n--;
return n;
}

@ -0,0 +1,65 @@
/*
* Copyright © 2012 Intel Corporation
*
* Permission to use, copy, modify, distribute, and sell this software and
* its documentation for any purpose is hereby granted without fee, provided
* that the above copyright notice appear in all copies and that both that
* copyright notice and this permission notice appear in supporting
* documentation, and that the name of the copyright holders not be used in
* advertising or publicity pertaining to distribution of the software
* without specific, written prior permission. The copyright holders make
* no representations about the suitability of this software for any
* purpose. It is provided "as is" without express or implied warranty.
*
* THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS
* SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS, IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY
* SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
* RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF
* CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#ifndef _WESTON_VERTEX_CLIPPING_H
#define _WESTON_VERTEX_CLIPPING_H
#include <GLES2/gl2.h>
struct polygon8 {
GLfloat x[8];
GLfloat y[8];
int n;
};
struct clip_context {
struct {
GLfloat x;
GLfloat y;
} prev;
struct {
GLfloat x1, y1;
GLfloat x2, y2;
} clip;
struct {
GLfloat *x;
GLfloat *y;
} vertices;
};
GLfloat
float_difference(GLfloat a, GLfloat b);
int
clip_simple(struct clip_context *ctx,
struct polygon8 *surf,
GLfloat *ex,
GLfloat *ey);
int
clip_transformed(struct clip_context *ctx,
struct polygon8 *surf,
GLfloat *ex,
GLfloat *ey);\
#endif
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