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SDL_Rect: Added floating point versions of all the rectangle APIs.

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Fixes #5110.
This commit is contained in:
Ryan C. Gordon 2022-03-19 10:27:31 -04:00
parent 4d9bef604a
commit d81fee7623
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GPG key ID: FA148B892AB48044
6 changed files with 608 additions and 470 deletions
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122
include/SDL_rect.h
View file

@ -54,8 +54,13 @@ typedef struct SDL_Point
/**
* The structure that defines a point (floating point)
*
* \sa SDL_EnclosePoints
* \sa SDL_PointInRect
* \sa SDL_FRectEmpty
* \sa SDL_FRectEquals
* \sa SDL_HasIntersectionF
* \sa SDL_IntersectFRect
* \sa SDL_UnionFRect
* \sa SDL_EncloseFPoints
* \sa SDL_PointInFRect
*/
typedef struct SDL_FPoint
{
@ -213,6 +218,119 @@ extern DECLSPEC SDL_bool SDLCALL SDL_IntersectRectAndLine(const SDL_Rect *
int *Y1, int *X2,
int *Y2);
/* SDL_FRect versions... */
/**
* Returns true if point resides inside a rectangle.
*/
SDL_FORCE_INLINE SDL_bool SDL_PointInFRect(const SDL_FPoint *p, const SDL_FRect *r)
{
return ( (p->x >= r->x) && (p->x < (r->x + r->w)) &&
(p->y >= r->y) && (p->y < (r->y + r->h)) ) ? SDL_TRUE : SDL_FALSE;
}
/**
* Returns true if the rectangle has no area.
*/
SDL_FORCE_INLINE SDL_bool SDL_FRectEmpty(const SDL_FRect *r)
{
return ((!r) || (r->w <= 0.0f) || (r->h <= 0.0f)) ? SDL_TRUE : SDL_FALSE;
}
/**
* Returns true if the two rectangles are equal.
*/
SDL_FORCE_INLINE SDL_bool SDL_FRectEquals(const SDL_FRect *a, const SDL_FRect *b)
{
return (a && b && (a->x == b->x) && (a->y == b->y) &&
(a->w == b->w) && (a->h == b->h)) ? SDL_TRUE : SDL_FALSE;
}
/**
* Determine whether two rectangles intersect with float precision.
*
* If either pointer is NULL the function will return SDL_FALSE.
*
* \param A an SDL_FRect structure representing the first rectangle
* \param B an SDL_FRect structure representing the second rectangle
* \returns SDL_TRUE if there is an intersection, SDL_FALSE otherwise.
*
* \sa SDL_IntersectRect
*/
extern DECLSPEC SDL_bool SDLCALL SDL_HasIntersectionF(const SDL_FRect * A,
const SDL_FRect * B);
/**
* Calculate the intersection of two rectangles with float precision.
*
* If `result` is NULL then this function will return SDL_FALSE.
*
* \param A an SDL_FRect structure representing the first rectangle
* \param B an SDL_FRect structure representing the second rectangle
* \param result an SDL_FRect structure filled in with the intersection of
* rectangles `A` and `B`
* \returns SDL_TRUE if there is an intersection, SDL_FALSE otherwise.
*
* \sa SDL_HasIntersectionF
*/
extern DECLSPEC SDL_bool SDLCALL SDL_IntersectFRect(const SDL_FRect * A,
const SDL_FRect * B,
SDL_FRect * result);
/**
* Calculate the union of two rectangles with float precision.
*
* \param A an SDL_FRect structure representing the first rectangle
* \param B an SDL_FRect structure representing the second rectangle
* \param result an SDL_FRect structure filled in with the union of rectangles
* `A` and `B`
*/
extern DECLSPEC void SDLCALL SDL_UnionFRect(const SDL_FRect * A,
const SDL_FRect * B,
SDL_FRect * result);
/**
* Calculate a minimal rectangle enclosing a set of points with float precision.
*
* If `clip` is not NULL then only points inside of the clipping rectangle are
* considered.
*
* \param points an array of SDL_FPoint structures representing points to be
* enclosed
* \param count the number of structures in the `points` array
* \param clip an SDL_FRect used for clipping or NULL to enclose all points
* \param result an SDL_FRect structure filled in with the minimal enclosing
* rectangle
* \returns SDL_TRUE if any points were enclosed or SDL_FALSE if all the
* points were outside of the clipping rectangle.
*/
extern DECLSPEC SDL_bool SDLCALL SDL_EncloseFPoints(const SDL_FPoint * points,
int count,
const SDL_FRect * clip,
SDL_FRect * result);
/**
* Calculate the intersection of a rectangle and line segment with float precision.
*
* This function is used to clip a line segment to a rectangle. A line segment
* contained entirely within the rectangle or that does not intersect will
* remain unchanged. A line segment that crosses the rectangle at either or
* both ends will be clipped to the boundary of the rectangle and the new
* coordinates saved in `X1`, `Y1`, `X2`, and/or `Y2` as necessary.
*
* \param rect an SDL_FRect structure representing the rectangle to intersect
* \param X1 a pointer to the starting X-coordinate of the line
* \param Y1 a pointer to the starting Y-coordinate of the line
* \param X2 a pointer to the ending X-coordinate of the line
* \param Y2 a pointer to the ending Y-coordinate of the line
* \returns SDL_TRUE if there is an intersection, SDL_FALSE otherwise.
*/
extern DECLSPEC SDL_bool SDLCALL SDL_IntersectFRectAndLine(const SDL_FRect *
rect, float *X1,
float *Y1, float *X2,
float *Y2);
/* Ends C function definitions when using C++ */
#ifdef __cplusplus
}

5
src/dynapi/SDL_dynapi_overrides.h
View file

@ -859,3 +859,8 @@
#define SDL_GetTouchName SDL_GetTouchName_REAL
#define SDL_ClearComposition SDL_ClearComposition_REAL
#define SDL_IsTextInputShown SDL_IsTextInputShown_REAL
#define SDL_HasIntersectionF SDL_HasIntersectionF_REAL
#define SDL_IntersectFRect SDL_IntersectFRect_REAL
#define SDL_UnionFRect SDL_UnionFRect_REAL
#define SDL_EncloseFPoints SDL_EncloseFPoints_REAL
#define SDL_IntersectFRectAndLine SDL_IntersectFRectAndLine_REAL

5
src/dynapi/SDL_dynapi_procs.h
View file

@ -930,3 +930,8 @@ SDL_DYNAPI_PROC(int,SDL_AndroidSendMessage,(Uint32 a, int b),(a,b),return)
SDL_DYNAPI_PROC(const char*,SDL_GetTouchName,(int a),(a),return)
SDL_DYNAPI_PROC(void,SDL_ClearComposition,(void),(),)
SDL_DYNAPI_PROC(SDL_bool,SDL_IsTextInputShown,(void),(),return)
SDL_DYNAPI_PROC(SDL_bool,SDL_HasIntersectionF,(const SDL_FRect *a, const SDL_FRect *b),(a,b),return)
SDL_DYNAPI_PROC(SDL_bool,SDL_IntersectFRect,(const SDL_FRect *a, const SDL_FRect *b, SDL_FRect *c),(a,b,c),return)
SDL_DYNAPI_PROC(void,SDL_UnionFRect,(const SDL_FRect *a, const SDL_FRect *b, SDL_FRect *c),(a,b,c),)
SDL_DYNAPI_PROC(SDL_bool,SDL_EncloseFPoints,(const SDL_FPoint *a, int b, const SDL_FRect *c, SDL_FRect *d),(a,b,c,d),return)
SDL_DYNAPI_PROC(SDL_bool,SDL_IntersectFRectAndLine,(const SDL_FRect *a, float *b, float *c, float *d, float *e),(a,b,c,d,e),return)

54
src/render/SDL_render.c
View file

@ -3382,60 +3382,6 @@ SDL_RenderFillRectsF(SDL_Renderer * renderer,
return retval < 0 ? retval : FlushRenderCommandsIfNotBatching(renderer);
}
/* !!! FIXME: move this to a public API if we want to do float versions of all of these later */
SDL_FORCE_INLINE SDL_bool SDL_FRectEmpty(const SDL_FRect *r)
{
return ((!r) || (r->w <= 0.0f) || (r->h <= 0.0f)) ? SDL_TRUE : SDL_FALSE;
}
/* !!! FIXME: move this to a public API if we want to do float versions of all of these later */
static SDL_bool
SDL_HasIntersectionF(const SDL_FRect * A, const SDL_FRect * B)
{
float Amin, Amax, Bmin, Bmax;
if (!A) {
SDL_InvalidParamError("A");
return SDL_FALSE;
}
if (!B) {
SDL_InvalidParamError("B");
return SDL_FALSE;
}
/* Special cases for empty rects */
if (SDL_FRectEmpty(A) || SDL_FRectEmpty(B)) {
return SDL_FALSE;
}
/* Horizontal intersection */
Amin = A->x;
Amax = Amin + A->w;
Bmin = B->x;
Bmax = Bmin + B->w;
if (Bmin > Amin)
Amin = Bmin;
if (Bmax < Amax)
Amax = Bmax;
if (Amax <= Amin)
return SDL_FALSE;
/* Vertical intersection */
Amin = A->y;
Amax = Amin + A->h;
Bmin = B->y;
Bmax = Bmin + B->h;
if (Bmin > Amin)
Amin = Bmin;
if (Bmax < Amax)
Amax = Bmax;
if (Amax <= Amin)
return SDL_FALSE;
return SDL_TRUE;
}
int
SDL_RenderCopy(SDL_Renderer * renderer, SDL_Texture * texture,
const SDL_Rect * srcrect, const SDL_Rect * dstrect)

448
src/video/SDL_rect.c
View file

@ -23,420 +23,8 @@
#include "SDL_rect.h"
#include "SDL_rect_c.h"
SDL_bool
SDL_HasIntersection(const SDL_Rect * A, const SDL_Rect * B)
{
int Amin, Amax, Bmin, Bmax;
if (!A) {
SDL_InvalidParamError("A");
return SDL_FALSE;
} else if (!B) {
SDL_InvalidParamError("B");
return SDL_FALSE;
} else if (SDL_RectEmpty(A) || SDL_RectEmpty(B)) {
return SDL_FALSE; /* Special cases for empty rects */
}
/* Horizontal intersection */
Amin = A->x;
Amax = Amin + A->w;
Bmin = B->x;
Bmax = Bmin + B->w;
if (Bmin > Amin) {
Amin = Bmin;
}
if (Bmax < Amax) {
Amax = Bmax;
}
if (Amax <= Amin) {
return SDL_FALSE;
}
/* Vertical intersection */
Amin = A->y;
Amax = Amin + A->h;
Bmin = B->y;
Bmax = Bmin + B->h;
if (Bmin > Amin) {
Amin = Bmin;
}
if (Bmax < Amax) {
Amax = Bmax;
}
if (Amax <= Amin) {
return SDL_FALSE;
}
return SDL_TRUE;
}
SDL_bool
SDL_IntersectRect(const SDL_Rect * A, const SDL_Rect * B, SDL_Rect * result)
{
int Amin, Amax, Bmin, Bmax;
if (!A) {
SDL_InvalidParamError("A");
return SDL_FALSE;
} else if (!B) {
SDL_InvalidParamError("B");
return SDL_FALSE;
} else if (!result) {
SDL_InvalidParamError("result");
return SDL_FALSE;
} else if (SDL_RectEmpty(A) || SDL_RectEmpty(B)) { /* Special cases for empty rects */
result->w = 0;
result->h = 0;
return SDL_FALSE;
}
/* Horizontal intersection */
Amin = A->x;
Amax = Amin + A->w;
Bmin = B->x;
Bmax = Bmin + B->w;
if (Bmin > Amin) {
Amin = Bmin;
}
result->x = Amin;
if (Bmax < Amax) {
Amax = Bmax;
}
result->w = Amax - Amin;
/* Vertical intersection */
Amin = A->y;
Amax = Amin + A->h;
Bmin = B->y;
Bmax = Bmin + B->h;
if (Bmin > Amin) {
Amin = Bmin;
}
result->y = Amin;
if (Bmax < Amax) {
Amax = Bmax;
}
result->h = Amax - Amin;
return !SDL_RectEmpty(result);
}
void
SDL_UnionRect(const SDL_Rect * A, const SDL_Rect * B, SDL_Rect * result)
{
int Amin, Amax, Bmin, Bmax;
if (!A) {
SDL_InvalidParamError("A");
return;
} else if (!B) {
SDL_InvalidParamError("B");
return;
} else if (!result) {
SDL_InvalidParamError("result");
return;
} else if (SDL_RectEmpty(A)) { /* Special cases for empty Rects */
if (SDL_RectEmpty(B)) { /* A and B empty */
SDL_zerop(result);
} else { /* A empty, B not empty */
*result = *B;
}
return;
} else if (SDL_RectEmpty(B)) { /* A not empty, B empty */
*result = *A;
return;
}
/* Horizontal union */
Amin = A->x;
Amax = Amin + A->w;
Bmin = B->x;
Bmax = Bmin + B->w;
if (Bmin < Amin) {
Amin = Bmin;
}
result->x = Amin;
if (Bmax > Amax) {
Amax = Bmax;
}
result->w = Amax - Amin;
/* Vertical union */
Amin = A->y;
Amax = Amin + A->h;
Bmin = B->y;
Bmax = Bmin + B->h;
if (Bmin < Amin) {
Amin = Bmin;
}
result->y = Amin;
if (Bmax > Amax) {
Amax = Bmax;
}
result->h = Amax - Amin;
}
SDL_bool
SDL_EnclosePoints(const SDL_Point * points, int count, const SDL_Rect * clip,
SDL_Rect * result)
{
int minx = 0;
int miny = 0;
int maxx = 0;
int maxy = 0;
int x, y, i;
if (!points) {
SDL_InvalidParamError("points");
return SDL_FALSE;
} else if (count < 1) {
SDL_InvalidParamError("count");
return SDL_FALSE;
}
if (clip) {
SDL_bool added = SDL_FALSE;
const int clip_minx = clip->x;
const int clip_miny = clip->y;
const int clip_maxx = clip->x+clip->w-1;
const int clip_maxy = clip->y+clip->h-1;
/* Special case for empty rectangle */
if (SDL_RectEmpty(clip)) {
return SDL_FALSE;
}
for (i = 0; i < count; ++i) {
x = points[i].x;
y = points[i].y;
if (x < clip_minx || x > clip_maxx ||
y < clip_miny || y > clip_maxy) {
continue;
}
if (!added) {
/* Special case: if no result was requested, we are done */
if (result == NULL) {
return SDL_TRUE;
}
/* First point added */
minx = maxx = x;
miny = maxy = y;
added = SDL_TRUE;
continue;
}
if (x < minx) {
minx = x;
} else if (x > maxx) {
maxx = x;
}
if (y < miny) {
miny = y;
} else if (y > maxy) {
maxy = y;
}
}
if (!added) {
return SDL_FALSE;
}
} else {
/* Special case: if no result was requested, we are done */
if (result == NULL) {
return SDL_TRUE;
}
/* No clipping, always add the first point */
minx = maxx = points[0].x;
miny = maxy = points[0].y;
for (i = 1; i < count; ++i) {
x = points[i].x;
y = points[i].y;
if (x < minx) {
minx = x;
} else if (x > maxx) {
maxx = x;
}
if (y < miny) {
miny = y;
} else if (y > maxy) {
maxy = y;
}
}
}
if (result) {
result->x = minx;
result->y = miny;
result->w = (maxx-minx)+1;
result->h = (maxy-miny)+1;
}
return SDL_TRUE;
}
/* Use the Cohen-Sutherland algorithm for line clipping */
#define CODE_BOTTOM 1
#define CODE_TOP 2
#define CODE_LEFT 4
#define CODE_RIGHT 8
static int
ComputeOutCode(const SDL_Rect * rect, int x, int y)
{
int code = 0;
if (y < rect->y) {
code |= CODE_TOP;
} else if (y >= rect->y + rect->h) {
code |= CODE_BOTTOM;
}
if (x < rect->x) {
code |= CODE_LEFT;
} else if (x >= rect->x + rect->w) {
code |= CODE_RIGHT;
}
return code;
}
SDL_bool
SDL_IntersectRectAndLine(const SDL_Rect * rect, int *X1, int *Y1, int *X2,
int *Y2)
{
int x = 0;
int y = 0;
int x1, y1;
int x2, y2;
int rectx1;
int recty1;
int rectx2;
int recty2;
int outcode1, outcode2;
if (!rect) {
SDL_InvalidParamError("rect");
return SDL_FALSE;
} else if (!X1) {
SDL_InvalidParamError("X1");
return SDL_FALSE;
} else if (!Y1) {
SDL_InvalidParamError("Y1");
return SDL_FALSE;
} else if (!X2) {
SDL_InvalidParamError("X2");
return SDL_FALSE;
} else if (!Y2) {
SDL_InvalidParamError("Y2");
return SDL_FALSE;
} else if (SDL_RectEmpty(rect)) {
return SDL_FALSE; /* Special case for empty rect */
}
x1 = *X1;
y1 = *Y1;
x2 = *X2;
y2 = *Y2;
rectx1 = rect->x;
recty1 = rect->y;
rectx2 = rect->x + rect->w - 1;
recty2 = rect->y + rect->h - 1;
/* Check to see if entire line is inside rect */
if (x1 >= rectx1 && x1 <= rectx2 && x2 >= rectx1 && x2 <= rectx2 &&
y1 >= recty1 && y1 <= recty2 && y2 >= recty1 && y2 <= recty2) {
return SDL_TRUE;
}
/* Check to see if entire line is to one side of rect */
if ((x1 < rectx1 && x2 < rectx1) || (x1 > rectx2 && x2 > rectx2) ||
(y1 < recty1 && y2 < recty1) || (y1 > recty2 && y2 > recty2)) {
return SDL_FALSE;
}
if (y1 == y2) { /* Horizontal line, easy to clip */
if (x1 < rectx1) {
*X1 = rectx1;
} else if (x1 > rectx2) {
*X1 = rectx2;
}
if (x2 < rectx1) {
*X2 = rectx1;
} else if (x2 > rectx2) {
*X2 = rectx2;
}
return SDL_TRUE;
}
if (x1 == x2) { /* Vertical line, easy to clip */
if (y1 < recty1) {
*Y1 = recty1;
} else if (y1 > recty2) {
*Y1 = recty2;
}
if (y2 < recty1) {
*Y2 = recty1;
} else if (y2 > recty2) {
*Y2 = recty2;
}
return SDL_TRUE;
}
/* More complicated Cohen-Sutherland algorithm */
outcode1 = ComputeOutCode(rect, x1, y1);
outcode2 = ComputeOutCode(rect, x2, y2);
while (outcode1 || outcode2) {
if (outcode1 & outcode2) {
return SDL_FALSE;
}
if (outcode1) {
if (outcode1 & CODE_TOP) {
y = recty1;
x = x1 + ((x2 - x1) * (y - y1)) / (y2 - y1);
} else if (outcode1 & CODE_BOTTOM) {
y = recty2;
x = x1 + ((x2 - x1) * (y - y1)) / (y2 - y1);
} else if (outcode1 & CODE_LEFT) {
x = rectx1;
y = y1 + ((y2 - y1) * (x - x1)) / (x2 - x1);
} else if (outcode1 & CODE_RIGHT) {
x = rectx2;
y = y1 + ((y2 - y1) * (x - x1)) / (x2 - x1);
}
x1 = x;
y1 = y;
outcode1 = ComputeOutCode(rect, x, y);
} else {
if (outcode2 & CODE_TOP) {
y = recty1;
x = x1 + ((x2 - x1) * (y - y1)) / (y2 - y1);
} else if (outcode2 & CODE_BOTTOM) {
y = recty2;
x = x1 + ((x2 - x1) * (y - y1)) / (y2 - y1);
} else if (outcode2 & CODE_LEFT) {
/* If this assertion ever fires, here's the static analysis that warned about it:
http://buildbot.libsdl.org/sdl-static-analysis/sdl-macosx-static-analysis/sdl-macosx-static-analysis-1101/report-b0d01a.html#EndPath */
SDL_assert(x2 != x1); /* if equal: division by zero. */
x = rectx1;
y = y1 + ((y2 - y1) * (x - x1)) / (x2 - x1);
} else if (outcode2 & CODE_RIGHT) {
/* If this assertion ever fires, here's the static analysis that warned about it:
http://buildbot.libsdl.org/sdl-static-analysis/sdl-macosx-static-analysis/sdl-macosx-static-analysis-1101/report-39b114.html#EndPath */
SDL_assert(x2 != x1); /* if equal: division by zero. */
x = rectx2;
y = y1 + ((y2 - y1) * (x - x1)) / (x2 - x1);
}
x2 = x;
y2 = y;
outcode2 = ComputeOutCode(rect, x, y);
}
}
*X1 = x1;
*Y1 = y1;
*X2 = x2;
*Y2 = y2;
return SDL_TRUE;
}
/* There's no float version of this at the moment, because it's not a public API
and internally we only need the int version. */
SDL_bool
SDL_GetSpanEnclosingRect(int width, int height,
int numrects, const SDL_Rect * rects, SDL_Rect *span)
@ -492,4 +80,36 @@ SDL_GetSpanEnclosingRect(int width, int height,
return SDL_FALSE;
}
/* For use with the Cohen-Sutherland algorithm for line clipping, in SDL_rect_impl.h */
#define CODE_BOTTOM 1
#define CODE_TOP 2
#define CODE_LEFT 4
#define CODE_RIGHT 8
/* Same code twice, for float and int versions... */
#define RECTTYPE SDL_Rect
#define POINTTYPE SDL_Point
#define SCALARTYPE int
#define COMPUTEOUTCODE ComputeOutCode
#define SDL_HASINTERSECTION SDL_HasIntersection
#define SDL_INTERSECTRECT SDL_IntersectRect
#define SDL_RECTEMPTY SDL_RectEmpty
#define SDL_UNIONRECT SDL_UnionRect
#define SDL_ENCLOSEPOINTS SDL_EnclosePoints
#define SDL_INTERSECTRECTANDLINE SDL_IntersectRectAndLine
#include "SDL_rect_impl.h"
#define RECTTYPE SDL_FRect
#define POINTTYPE SDL_FPoint
#define SCALARTYPE float
#define COMPUTEOUTCODE ComputeOutCodeF
#define SDL_HASINTERSECTION SDL_HasIntersectionF
#define SDL_INTERSECTRECT SDL_IntersectFRect
#define SDL_RECTEMPTY SDL_FRectEmpty
#define SDL_UNIONRECT SDL_UnionFRect
#define SDL_ENCLOSEPOINTS SDL_EncloseFPoints
#define SDL_INTERSECTRECTANDLINE SDL_IntersectFRectAndLine
#include "SDL_rect_impl.h"
/* vi: set ts=4 sw=4 expandtab: */

444
src/video/SDL_rect_impl.h Normal file
View file

@ -0,0 +1,444 @@
/*
Simple DirectMedia Layer
Copyright (C) 1997-2022 Sam Lantinga <slouken@libsdl.org>
This software is provided 'as-is', without any express or implied
warranty. In no event will the authors be held liable for any damages
arising from the use of this software.
Permission is granted to anyone to use this software for any purpose,
including commercial applications, and to alter it and redistribute it
freely, subject to the following restrictions:
1. The origin of this software must not be misrepresented; you must not
claim that you wrote the original software. If you use this software
in a product, an acknowledgment in the product documentation would be
appreciated but is not required.
2. Altered source versions must be plainly marked as such, and must not be
misrepresented as being the original software.
3. This notice may not be removed or altered from any source distribution.
*/
/* This file is #included twice to support int and float versions with the same code. */
SDL_bool
SDL_HASINTERSECTION(const RECTTYPE * A, const RECTTYPE * B)
{
SCALARTYPE Amin, Amax, Bmin, Bmax;
if (!A) {
SDL_InvalidParamError("A");
return SDL_FALSE;
} else if (!B) {
SDL_InvalidParamError("B");
return SDL_FALSE;
} else if (SDL_RECTEMPTY(A) || SDL_RECTEMPTY(B)) {
return SDL_FALSE; /* Special cases for empty rects */
}
/* Horizontal intersection */
Amin = A->x;
Amax = Amin + A->w;
Bmin = B->x;
Bmax = Bmin + B->w;
if (Bmin > Amin) {
Amin = Bmin;
}
if (Bmax < Amax) {
Amax = Bmax;
}
if (Amax <= Amin) {
return SDL_FALSE;
}
/* Vertical intersection */
Amin = A->y;
Amax = Amin + A->h;
Bmin = B->y;
Bmax = Bmin + B->h;
if (Bmin > Amin) {
Amin = Bmin;
}
if (Bmax < Amax) {
Amax = Bmax;
}
if (Amax <= Amin) {
return SDL_FALSE;
}
return SDL_TRUE;
}
SDL_bool
SDL_INTERSECTRECT(const RECTTYPE * A, const RECTTYPE * B, RECTTYPE * result)
{
SCALARTYPE Amin, Amax, Bmin, Bmax;
if (!A) {
SDL_InvalidParamError("A");
return SDL_FALSE;
} else if (!B) {
SDL_InvalidParamError("B");
return SDL_FALSE;
} else if (!result) {
SDL_InvalidParamError("result");
return SDL_FALSE;
} else if (SDL_RECTEMPTY(A) || SDL_RECTEMPTY(B)) { /* Special cases for empty rects */
result->w = 0;
result->h = 0;
return SDL_FALSE;
}
/* Horizontal intersection */
Amin = A->x;
Amax = Amin + A->w;
Bmin = B->x;
Bmax = Bmin + B->w;
if (Bmin > Amin) {
Amin = Bmin;
}
result->x = Amin;
if (Bmax < Amax) {
Amax = Bmax;
}
result->w = Amax - Amin;
/* Vertical intersection */
Amin = A->y;
Amax = Amin + A->h;
Bmin = B->y;
Bmax = Bmin + B->h;
if (Bmin > Amin) {
Amin = Bmin;
}
result->y = Amin;
if (Bmax < Amax) {
Amax = Bmax;
}
result->h = Amax - Amin;
return !SDL_RECTEMPTY(result);
}
void
SDL_UNIONRECT(const RECTTYPE * A, const RECTTYPE * B, RECTTYPE * result)
{
SCALARTYPE Amin, Amax, Bmin, Bmax;
if (!A) {
SDL_InvalidParamError("A");
return;
} else if (!B) {
SDL_InvalidParamError("B");
return;
} else if (!result) {
SDL_InvalidParamError("result");
return;
} else if (SDL_RECTEMPTY(A)) { /* Special cases for empty Rects */
if (SDL_RECTEMPTY(B)) { /* A and B empty */
SDL_zerop(result);
} else { /* A empty, B not empty */
*result = *B;
}
return;
} else if (SDL_RECTEMPTY(B)) { /* A not empty, B empty */
*result = *A;
return;
}
/* Horizontal union */
Amin = A->x;
Amax = Amin + A->w;
Bmin = B->x;
Bmax = Bmin + B->w;
if (Bmin < Amin) {
Amin = Bmin;
}
result->x = Amin;
if (Bmax > Amax) {
Amax = Bmax;
}
result->w = Amax - Amin;
/* Vertical union */
Amin = A->y;
Amax = Amin + A->h;
Bmin = B->y;
Bmax = Bmin + B->h;
if (Bmin < Amin) {
Amin = Bmin;
}
result->y = Amin;
if (Bmax > Amax) {
Amax = Bmax;
}
result->h = Amax - Amin;
}
SDL_bool SDL_ENCLOSEPOINTS(const POINTTYPE * points, int count, const RECTTYPE * clip,
RECTTYPE * result)
{
SCALARTYPE minx = 0;
SCALARTYPE miny = 0;
SCALARTYPE maxx = 0;
SCALARTYPE maxy = 0;
SCALARTYPE x, y;
int i;
if (!points) {
SDL_InvalidParamError("points");
return SDL_FALSE;
} else if (count < 1) {
SDL_InvalidParamError("count");
return SDL_FALSE;
}
if (clip) {
SDL_bool added = SDL_FALSE;
const SCALARTYPE clip_minx = clip->x;
const SCALARTYPE clip_miny = clip->y;
const SCALARTYPE clip_maxx = clip->x+clip->w-1;
const SCALARTYPE clip_maxy = clip->y+clip->h-1;
/* Special case for empty rectangle */
if (SDL_RECTEMPTY(clip)) {
return SDL_FALSE;
}
for (i = 0; i < count; ++i) {
x = points[i].x;
y = points[i].y;
if (x < clip_minx || x > clip_maxx ||
y < clip_miny || y > clip_maxy) {
continue;
}
if (!added) {
/* Special case: if no result was requested, we are done */
if (result == NULL) {
return SDL_TRUE;
}
/* First point added */
minx = maxx = x;
miny = maxy = y;
added = SDL_TRUE;
continue;
}
if (x < minx) {
minx = x;
} else if (x > maxx) {
maxx = x;
}
if (y < miny) {
miny = y;
} else if (y > maxy) {
maxy = y;
}
}
if (!added) {
return SDL_FALSE;
}
} else {
/* Special case: if no result was requested, we are done */
if (result == NULL) {
return SDL_TRUE;
}
/* No clipping, always add the first point */
minx = maxx = points[0].x;
miny = maxy = points[0].y;
for (i = 1; i < count; ++i) {
x = points[i].x;
y = points[i].y;
if (x < minx) {
minx = x;
} else if (x > maxx) {
maxx = x;
}
if (y < miny) {
miny = y;
} else if (y > maxy) {
maxy = y;
}
}
}
if (result) {
result->x = minx;
result->y = miny;
result->w = (maxx-minx)+1;
result->h = (maxy-miny)+1;
}
return SDL_TRUE;
}
/* Use the Cohen-Sutherland algorithm for line clipping */
static int
COMPUTEOUTCODE(const RECTTYPE * rect, SCALARTYPE x, SCALARTYPE y)
{
int code = 0;
if (y < rect->y) {
code |= CODE_TOP;
} else if (y >= rect->y + rect->h) {
code |= CODE_BOTTOM;
}
if (x < rect->x) {
code |= CODE_LEFT;
} else if (x >= rect->x + rect->w) {
code |= CODE_RIGHT;
}
return code;
}
SDL_bool
SDL_INTERSECTRECTANDLINE(const RECTTYPE * rect, SCALARTYPE *X1, SCALARTYPE *Y1, SCALARTYPE *X2,
SCALARTYPE *Y2)
{
SCALARTYPE x = 0;
SCALARTYPE y = 0;
SCALARTYPE x1, y1;
SCALARTYPE x2, y2;
SCALARTYPE rectx1;
SCALARTYPE recty1;
SCALARTYPE rectx2;
SCALARTYPE recty2;
int outcode1, outcode2;
if (!rect) {
SDL_InvalidParamError("rect");
return SDL_FALSE;
} else if (!X1) {
SDL_InvalidParamError("X1");
return SDL_FALSE;
} else if (!Y1) {
SDL_InvalidParamError("Y1");
return SDL_FALSE;
} else if (!X2) {
SDL_InvalidParamError("X2");
return SDL_FALSE;
} else if (!Y2) {
SDL_InvalidParamError("Y2");
return SDL_FALSE;
} else if (SDL_RECTEMPTY(rect)) {
return SDL_FALSE; /* Special case for empty rect */
}
x1 = *X1;
y1 = *Y1;
x2 = *X2;
y2 = *Y2;
rectx1 = rect->x;
recty1 = rect->y;
rectx2 = rect->x + rect->w - 1;
recty2 = rect->y + rect->h - 1;
/* Check to see if entire line is inside rect */
if (x1 >= rectx1 && x1 <= rectx2 && x2 >= rectx1 && x2 <= rectx2 &&
y1 >= recty1 && y1 <= recty2 && y2 >= recty1 && y2 <= recty2) {
return SDL_TRUE;
}
/* Check to see if entire line is to one side of rect */
if ((x1 < rectx1 && x2 < rectx1) || (x1 > rectx2 && x2 > rectx2) ||
(y1 < recty1 && y2 < recty1) || (y1 > recty2 && y2 > recty2)) {
return SDL_FALSE;
}
if (y1 == y2) { /* Horizontal line, easy to clip */
if (x1 < rectx1) {
*X1 = rectx1;
} else if (x1 > rectx2) {
*X1 = rectx2;
}
if (x2 < rectx1) {
*X2 = rectx1;
} else if (x2 > rectx2) {
*X2 = rectx2;
}
return SDL_TRUE;
}
if (x1 == x2) { /* Vertical line, easy to clip */
if (y1 < recty1) {
*Y1 = recty1;
} else if (y1 > recty2) {
*Y1 = recty2;
}
if (y2 < recty1) {
*Y2 = recty1;
} else if (y2 > recty2) {
*Y2 = recty2;
}
return SDL_TRUE;
}
/* More complicated Cohen-Sutherland algorithm */
outcode1 = COMPUTEOUTCODE(rect, x1, y1);
outcode2 = COMPUTEOUTCODE(rect, x2, y2);
while (outcode1 || outcode2) {
if (outcode1 & outcode2) {
return SDL_FALSE;
}
if (outcode1) {
if (outcode1 & CODE_TOP) {
y = recty1;
x = x1 + ((x2 - x1) * (y - y1)) / (y2 - y1);
} else if (outcode1 & CODE_BOTTOM) {
y = recty2;
x = x1 + ((x2 - x1) * (y - y1)) / (y2 - y1);
} else if (outcode1 & CODE_LEFT) {
x = rectx1;
y = y1 + ((y2 - y1) * (x - x1)) / (x2 - x1);
} else if (outcode1 & CODE_RIGHT) {
x = rectx2;
y = y1 + ((y2 - y1) * (x - x1)) / (x2 - x1);
}
x1 = x;
y1 = y;
outcode1 = COMPUTEOUTCODE(rect, x, y);
} else {
if (outcode2 & CODE_TOP) {
y = recty1;
x = x1 + ((x2 - x1) * (y - y1)) / (y2 - y1);
} else if (outcode2 & CODE_BOTTOM) {
y = recty2;
x = x1 + ((x2 - x1) * (y - y1)) / (y2 - y1);
} else if (outcode2 & CODE_LEFT) {
/* If this assertion ever fires, here's the static analysis that warned about it:
http://buildbot.libsdl.org/sdl-static-analysis/sdl-macosx-static-analysis/sdl-macosx-static-analysis-1101/report-b0d01a.html#EndPath */
SDL_assert(x2 != x1); /* if equal: division by zero. */
x = rectx1;
y = y1 + ((y2 - y1) * (x - x1)) / (x2 - x1);
} else if (outcode2 & CODE_RIGHT) {
/* If this assertion ever fires, here's the static analysis that warned about it:
http://buildbot.libsdl.org/sdl-static-analysis/sdl-macosx-static-analysis/sdl-macosx-static-analysis-1101/report-39b114.html#EndPath */
SDL_assert(x2 != x1); /* if equal: division by zero. */
x = rectx2;
y = y1 + ((y2 - y1) * (x - x1)) / (x2 - x1);
}
x2 = x;
y2 = y;
outcode2 = COMPUTEOUTCODE(rect, x, y);
}
}
*X1 = x1;
*Y1 = y1;
*X2 = x2;
*Y2 = y2;
return SDL_TRUE;
}
#undef RECTTYPE
#undef POINTTYPE
#undef SCALARTYPE
#undef COMPUTEOUTCODE
#undef SDL_HASINTERSECTION
#undef SDL_INTERSECTRECT
#undef SDL_RECTEMPTY
#undef SDL_UNIONRECT
#undef SDL_ENCLOSEPOINTS
#undef SDL_INTERSECTRECTANDLINE
/* vi: set ts=4 sw=4 expandtab: */