SDL_rect.c
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/*
Simple DirectMedia Layer
Copyright (C) 1997-2018 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.
*/
#include "../SDL_internal.h"
#include "SDL_rect.h"
#include "SDL_rect_c.h"
#include "SDL_assert.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;
}
if (!B) {
SDL_InvalidParamError("B");
return SDL_FALSE;
}
/* Special cases for empty rects */
if (SDL_RectEmpty(A) || SDL_RectEmpty(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;
}
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;
}
if (!B) {
SDL_InvalidParamError("B");
return SDL_FALSE;
}
if (!result) {
SDL_InvalidParamError("result");
return SDL_FALSE;
}
/* Special cases for empty rects */
if (SDL_RectEmpty(A) || SDL_RectEmpty(B)) {
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;
}
if (!B) {
SDL_InvalidParamError("B");
return;
}
if (!result) {
SDL_InvalidParamError("result");
return;
}
/* Special cases for empty Rects */
if (SDL_RectEmpty(A)) {
if (SDL_RectEmpty(B)) {
/* A and B empty */
return;
} 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;
}
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;
}
if (!X1) {
SDL_InvalidParamError("X1");
return SDL_FALSE;
}
if (!Y1) {
SDL_InvalidParamError("Y1");
return SDL_FALSE;
}
if (!X2) {
SDL_InvalidParamError("X2");
return SDL_FALSE;
}
if (!Y2) {
SDL_InvalidParamError("Y2");
return SDL_FALSE;
}
/* Special case for empty rect */
if (SDL_RectEmpty(rect)) {
return SDL_FALSE;
}
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;
}
SDL_bool
SDL_GetSpanEnclosingRect(int width, int height,
int numrects, const SDL_Rect * rects, SDL_Rect *span)
{
int i;
int span_y1, span_y2;
int rect_y1, rect_y2;
if (width < 1) {
SDL_InvalidParamError("width");
return SDL_FALSE;
}
if (height < 1) {
SDL_InvalidParamError("height");
return SDL_FALSE;
}
if (!rects) {
SDL_InvalidParamError("rects");
return SDL_FALSE;
}
if (!span) {
SDL_InvalidParamError("span");
return SDL_FALSE;
}
if (numrects < 1) {
SDL_InvalidParamError("numrects");
return SDL_FALSE;
}
/* Initialize to empty rect */
span_y1 = height;
span_y2 = 0;
for (i = 0; i < numrects; ++i) {
rect_y1 = rects[i].y;
rect_y2 = rect_y1 + rects[i].h;
/* Clip out of bounds rectangles, and expand span rect */
if (rect_y1 < 0) {
span_y1 = 0;
} else if (rect_y1 < span_y1) {
span_y1 = rect_y1;
}
if (rect_y2 > height) {
span_y2 = height;
} else if (rect_y2 > span_y2) {
span_y2 = rect_y2;
}
}
if (span_y2 > span_y1) {
span->x = 0;
span->y = span_y1;
span->w = width;
span->h = (span_y2 - span_y1);
return SDL_TRUE;
}
return SDL_FALSE;
}
/* vi: set ts=4 sw=4 expandtab: */
SDL_UnionRect
void SDL_UnionRect(const SDL_Rect *A, const SDL_Rect *B, SDL_Rect *result)
Calculate the union of two rectangles.
Definition: SDL_rect.c:129
CODE_TOP
#define CODE_TOP
Definition: SDL_rect.c:295
x1
GLuint GLfloat GLfloat GLfloat x1
Definition: SDL_opengl_glext.h:8583
SDL_TRUE
Definition: SDL_stdinc.h:142
result
GLuint64EXT * result
Definition: SDL_opengl_glext.h:9432
x
GLint GLint GLint GLint GLint x
Definition: SDL_opengl.h:1574
count
GLuint GLuint GLsizei count
Definition: SDL_opengl.h:1571
rect
SDL_Rect rect
Definition: testrelative.c:27
SDL_rect_c.h
SDL_HasIntersection
SDL_bool SDL_HasIntersection(const SDL_Rect *A, const SDL_Rect *B)
Determine whether two rectangles intersect.
Definition: SDL_rect.c:28
SDL_FALSE
Definition: SDL_stdinc.h:141
CODE_RIGHT
#define CODE_RIGHT
Definition: SDL_rect.c:297
y2
GLfixed GLfixed GLfixed y2
Definition: SDL_opengl_glext.h:4583
SDL_Point
The structure that defines a point.
Definition: SDL_rect.h:48
CODE_BOTTOM
#define CODE_BOTTOM
Definition: SDL_rect.c:294
ComputeOutCode
static int ComputeOutCode(const SDL_Rect *rect, int x, int y)
Definition: SDL_rect.c:300
SDL_InvalidParamError
#define SDL_InvalidParamError(param)
Definition: SDL_error.h:54
SDL_RectEmpty
SDL_FORCE_INLINE SDL_bool SDL_RectEmpty(const SDL_Rect *r)
Returns true if the rectangle has no area.
Definition: SDL_rect.h:82
x2
GLfixed GLfixed x2
Definition: SDL_opengl_glext.h:4583
width
GLint GLint GLsizei width
Definition: SDL_opengl.h:1572
points
GLfixed GLfixed GLint GLint GLfixed points
Definition: SDL_opengl_glext.h:4558
y1
GLfixed y1
Definition: SDL_opengl_glext.h:4583
SDL_Point::x
int x
Definition: SDL_rect.h:50
SDL_Point::y
int y
Definition: SDL_rect.h:51
SDL_EnclosePoints
SDL_bool SDL_EnclosePoints(const SDL_Point *points, int count, const SDL_Rect *clip, SDL_Rect *result)
Calculate a minimal rectangle enclosing a set of points.
Definition: SDL_rect.c:192
SDL_IntersectRect
SDL_bool SDL_IntersectRect(const SDL_Rect *A, const SDL_Rect *B, SDL_Rect *result)
Calculate the intersection of two rectangles.
Definition: SDL_rect.c:75
CODE_LEFT
#define CODE_LEFT
Definition: SDL_rect.c:296
y
GLint GLint GLint GLint GLint GLint y
Definition: SDL_opengl.h:1574
SDL_Rect::x
int x
Definition: SDL_rect.h:66
SDL_Rect::w
int w
Definition: SDL_rect.h:67
i
return Display return Display Bool Bool int int int return Display XEvent Bool(*) XPointer return Display return Display Drawable _Xconst char unsigned int unsigned int return Display Pixmap Pixmap XColor XColor unsigned int unsigned int return Display _Xconst char char int char return Display Visual unsigned int int int char unsigned int unsigned int in i)
Definition: SDL_x11sym.h:50
SDL_assert
#define SDL_assert(condition)
Definition: SDL_assert.h:169
NULL
#define NULL
Definition: begin_code.h:164
SDL_bool
SDL_bool
Definition: SDL_stdinc.h:139
height
GLint GLint GLsizei GLsizei height
Definition: SDL_opengl.h:1572
SDL_Rect::h
int h
Definition: SDL_rect.h:67
span
GLenum GLenum void void void * span
Definition: SDL_opengl_glext.h:3138
rects
EGLSurface EGLint * rects
Definition: eglext.h:282
SDL_IntersectRectAndLine
SDL_bool SDL_IntersectRectAndLine(const SDL_Rect *rect, int *X1, int *Y1, int *X2, int *Y2)
Calculate the intersection of a rectangle and line segment.
Definition: SDL_rect.c:317
SDL_Rect::y
int y
Definition: SDL_rect.h:66
SDL_Rect
A rectangle, with the origin at the upper left.
Definition: SDL_rect.h:64
SDL_GetSpanEnclosingRect
SDL_bool SDL_GetSpanEnclosingRect(int width, int height, int numrects, const SDL_Rect *rects, SDL_Rect *span)
Definition: SDL_rect.c:469
SDL_assert.h
SDL_rect.h