Date: Sat, 3 Jan 2009 22:11:18 -0500
From: "Donny Viszneki" Subject: Re: [SDL] Want to help with SDL 1.3? >> > For example, here's a good quick project for someone from the TODO list: >> > * Add diagonal line clipping to SDL_IntersectRectAndLine() Just wanted to point out that the patch is available at http://codebad.com/rect-line-ix.patch I hereby grant Sam Lantinga an irrevocable non-exclusive distribution license to this patch to do with as he wishes. --HG-- extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/trunk%403456
This commit is contained in:
Sam Lantinga
parent
3ca7408da3
commit
522eb2b9e1
3 changed files with 434 additions and 4 deletions
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@ -148,13 +148,13 @@ SDL_IntersectRectAndLine(const SDL_Rect * rect, int *X1, int *Y1, int *X2,
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return SDL_TRUE;
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}
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/* Check to see if entire line is outside rect */
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/* Check to see if entire line is to one side of rect */
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if ((x1 < rectx1 && x2 < rectx1) || (x1 > rectx2 && x2 > rectx2) ||
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(y1 < recty1 && y2 < recty2) || (y1 > recty2 && y2 > recty2)) {
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return SDL_FALSE;
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}
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if (y1 = y2) {
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if (y1 == y2) {
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/* Horizontal line, easy to clip */
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if (x1 < rectx1) {
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*X1 = rectx1;
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@ -184,7 +184,92 @@ SDL_IntersectRectAndLine(const SDL_Rect * rect, int *X1, int *Y1, int *X2,
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return SDL_TRUE;
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}
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/* FIXME: need code to clip diagonal line to rect */
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else
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{
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/* The task of clipping a line with finite slope ratios in a fixed-
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* precision coordinate space is not as immediately simple as it is
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* with coordinates of arbitrary precision. If the ratio of slopes
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* between the input line segment and the result line segment is not
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* a whole number, you have in fact *moved* the line segment a bit,
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* and there can be no avoiding it without more precision
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*/
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int *x_result_[] = {X1, X2, NULL}, **x_result = x_result_;
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int *y_result_[] = {Y1, Y2, NULL}, **y_result = y_result_;
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SDL_bool intersection = SDL_FALSE;
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double b, m, left, right, bottom, top;
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int xl, xh, yl, yh;
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/* solve mx+b line formula */
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m = (double)(y1-y2) / (double)(x1-x2);
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b = y2 - m * (double) x2;
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/* find some linear intersections */
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left = (m * (double) rectx1) + b;
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right = (m * (double) rectx2) + b;
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top = (recty1 - b) / m;
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bottom = (recty2 - b) / m;
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/* sort end-points' x and y components individually */
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if (x1 < x2) {
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xl = x1;
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xh = x2;
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} else {
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xl = x2;
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xh = x1;
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}
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if (y1 < y2) {
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yl = y1;
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yh = y2;
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} else {
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yl = y2;
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yh = y1;
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}
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#define RISING(a, b, c) (((a)<=(b))&&((b)<=(c)))
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/* check for a point that's entirely inside the rect */
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if (RISING(rectx1, x1, rectx2) && RISING(recty1, y1, recty2)) {
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x_result++;
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y_result++;
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intersection = SDL_TRUE;
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} else /* it was determined earlier that *both* end-points are not contained */
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if (RISING(rectx1, x2, rectx2) && RISING(recty1, y2, recty2)) {
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**(x_result++) = x2;
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**(y_result++) = y2;
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intersection = SDL_TRUE;
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}
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if (RISING(recty1, left, recty2) && RISING(xl, rectx1, xh)) {
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**(x_result++) = rectx1;
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**(y_result++) = (int) left;
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intersection = SDL_TRUE;
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}
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if (*x_result == NULL) return intersection;
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if (RISING(recty1, right, recty2) && RISING(xl, rectx2, xh)) {
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**(x_result++) = rectx2;
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**(y_result++) = (int) right;
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intersection = SDL_TRUE;
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}
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if (*x_result == NULL) return intersection;
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if (RISING(rectx1, top, rectx2) && RISING(yl, recty1, yh)) {
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**(x_result++) = (int) top;
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**(y_result++) = recty1;
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intersection = SDL_TRUE;
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}
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if (*x_result == NULL) return intersection;
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if (RISING(rectx1, bottom, rectx2) && RISING(yl, recty2, yh)) {
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**(x_result++) = (int) bottom;
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**(y_result++) = recty2;
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intersection = SDL_TRUE;
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}
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return intersection;
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}
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return SDL_FALSE;
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}
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@ -7,7 +7,7 @@ EXE = @EXE@
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CFLAGS = @CFLAGS@
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LIBS = @LIBS@
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TARGETS = checkkeys$(EXE) graywin$(EXE) loopwave$(EXE) testaudioinfo$(EXE) testmultiaudio$(EXE) testalpha$(EXE) testbitmap$(EXE) testblitspeed$(EXE) testcdrom$(EXE) testcursor$(EXE) testdraw2$(EXE) testdyngl$(EXE) testerror$(EXE) testfile$(EXE) testgamma$(EXE) testgl$(EXE) testgl2$(EXE) testhread$(EXE) testiconv$(EXE) testjoystick$(EXE) testkeys$(EXE) testlock$(EXE) testoverlay2$(EXE) testoverlay$(EXE) testpalette$(EXE) testplatform$(EXE) testsem$(EXE) testsprite$(EXE) testsprite2$(EXE) testtimer$(EXE) testver$(EXE) testvidinfo$(EXE) testwin$(EXE) testwm$(EXE) testwm2$(EXE) threadwin$(EXE) torturethread$(EXE) testloadso$(EXE) testhaptic$(EXE) testmmousetablet$(EXE)
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TARGETS = checkkeys$(EXE) graywin$(EXE) loopwave$(EXE) testaudioinfo$(EXE) testmultiaudio$(EXE) testalpha$(EXE) testbitmap$(EXE) testblitspeed$(EXE) testcdrom$(EXE) testcursor$(EXE) testintersections$(EXE) testdraw2$(EXE) testdyngl$(EXE) testerror$(EXE) testfile$(EXE) testgamma$(EXE) testgl$(EXE) testgl2$(EXE) testhread$(EXE) testiconv$(EXE) testjoystick$(EXE) testkeys$(EXE) testlock$(EXE) testoverlay2$(EXE) testoverlay$(EXE) testpalette$(EXE) testplatform$(EXE) testsem$(EXE) testsprite$(EXE) testsprite2$(EXE) testtimer$(EXE) testver$(EXE) testvidinfo$(EXE) testwin$(EXE) testwm$(EXE) testwm2$(EXE) threadwin$(EXE) torturethread$(EXE) testloadso$(EXE) testhaptic$(EXE) testmmousetablet$(EXE)
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all: Makefile $(TARGETS)
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@ -44,6 +44,9 @@ testcdrom$(EXE): $(srcdir)/testcdrom.c
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testcursor$(EXE): $(srcdir)/testcursor.c
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$(CC) -o $@ $? $(CFLAGS) $(LIBS)
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testintersections$(EXE): $(srcdir)/testintersections.c $(srcdir)/common.c
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$(CC) -o $@ $(srcdir)/testintersections.c $(srcdir)/common.c $(CFLAGS) $(LIBS)
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testdraw2$(EXE): $(srcdir)/testdraw2.c $(srcdir)/common.c
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$(CC) -o $@ $(srcdir)/testdraw2.c $(srcdir)/common.c $(CFLAGS) $(LIBS)
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342
test/testintersections.c
Normal file
342
test/testintersections.c
Normal file
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@ -0,0 +1,342 @@
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/* Simple program: draw as many random objects on the screen as possible */
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#include <stdlib.h>
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#include <stdio.h>
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#include <time.h>
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#include "common.h"
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#define SWAP(typ,a,b) do{typ t=a;a=b;b=t;}while(0)
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#define NUM_OBJECTS 100
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static CommonState *state;
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static int num_objects;
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static SDL_bool cycle_color;
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static SDL_bool cycle_alpha;
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static int cycle_direction = 1;
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static int current_alpha = 255;
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static int current_color = 255;
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static SDL_BlendMode blendMode = SDL_BLENDMODE_NONE;
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void
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DrawPoints(SDL_WindowID window)
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{
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int i;
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int x, y;
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int window_w, window_h;
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/* Query the sizes */
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SDL_GetWindowSize(window, &window_w, &window_h);
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SDL_SetRenderDrawBlendMode(blendMode);
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for (i = 0; i < num_objects * 4; ++i) {
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/* Cycle the color and alpha, if desired */
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if (cycle_color) {
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current_color += cycle_direction;
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if (current_color < 0) {
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current_color = 0;
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cycle_direction = -cycle_direction;
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}
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if (current_color > 255) {
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current_color = 255;
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cycle_direction = -cycle_direction;
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}
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}
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if (cycle_alpha) {
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current_alpha += cycle_direction;
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if (current_alpha < 0) {
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current_alpha = 0;
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cycle_direction = -cycle_direction;
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}
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if (current_alpha > 255) {
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current_alpha = 255;
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cycle_direction = -cycle_direction;
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}
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}
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SDL_SetRenderDrawColor(255, (Uint8) current_color,
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(Uint8) current_color, (Uint8) current_alpha);
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x = rand() % window_w;
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y = rand() % window_h;
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SDL_RenderPoint(x, y);
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}
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SDL_SetRenderDrawBlendMode(SDL_BLENDMODE_NONE);
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}
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#define MAX_LINES 16
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int num_lines = 0;
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SDL_Rect lines[MAX_LINES];
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static int add_line(int x1, int y1, int x2, int y2) {
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if (num_lines >= MAX_LINES) return 0;
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if ((x1 == x2) && (y1 == y2)) return 0;
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printf("adding line (%d, %d), (%d, %d)\n", x1, y1, x2, y2);
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lines[num_lines].x = x1;
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lines[num_lines].y = y1;
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lines[num_lines].w = x2;
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lines[num_lines].h = y2;
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return ++num_lines;
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}
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void
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DrawLines(SDL_WindowID window)
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{
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int i;
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int x1, y1, x2, y2;
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int window_w, window_h;
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/* Query the sizes */
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SDL_GetWindowSize(window, &window_w, &window_h);
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SDL_SetRenderDrawBlendMode(blendMode);
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for (i = 0; i < num_lines; ++i) {
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SDL_SetRenderDrawColor(255, 255, 255, 255);
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if (i == -1) {
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SDL_RenderLine(0, 0, window_w - 1, window_h - 1);
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SDL_RenderLine(0, window_h - 1, window_w - 1, 0);
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SDL_RenderLine(0, window_h / 2, window_w - 1, window_h / 2);
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SDL_RenderLine(window_w / 2, 0, window_w / 2, window_h - 1);
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} else {
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SDL_RenderLine(lines[i].x, lines[i].y, lines[i].w, lines[i].h);
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}
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}
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SDL_SetRenderDrawBlendMode(SDL_BLENDMODE_NONE);
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}
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#define MAX_RECTS 16
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int num_rects = 0;
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SDL_Rect rects[MAX_RECTS];
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static int add_rect(int x1, int y1, int x2, int y2) {
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if (num_rects >= MAX_RECTS) return 0;
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if ((x1 == x2) || (y1 == y2)) return 0;
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if (x1 > x2) SWAP(int, x1, x2);
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if (y1 > y2) SWAP(int, y1, y2);
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printf("adding rect (%d, %d), (%d, %d) [%dx%d]\n", x1, y1, x2, y2, x2-x1, y2-y1);
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rects[num_rects].x = x1;
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rects[num_rects].y = y1;
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rects[num_rects].w = x2 - x1;
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rects[num_rects].h = y2 - y1;
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return ++num_rects;
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}
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static void
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DrawRects(SDL_WindowID window)
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{
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int i;
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int window_w, window_h;
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/* Query the sizes */
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SDL_GetWindowSize(window, &window_w, &window_h);
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SDL_SetRenderDrawBlendMode(SDL_BLENDMODE_NONE);
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for (i = 0; i < num_rects; ++i) {
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SDL_SetRenderDrawColor(255, 127, 0, 255);
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SDL_RenderFill(&rects[i]);
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}
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SDL_SetRenderDrawBlendMode(SDL_BLENDMODE_NONE);
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}
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static void
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DrawRectLineIntersections(SDL_WindowID window)
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{
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int i, j, window_w, window_h;
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/* Query the sizes */
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SDL_GetWindowSize(window, &window_w, &window_h);
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SDL_SetRenderDrawBlendMode(SDL_BLENDMODE_NONE);
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for (i = 0; i < num_rects; i++)
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for (j = 0; j < num_lines; j++) {
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int x1, y1, x2, y2;
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SDL_Rect r;
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r = rects[i];
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x1 = lines[j].x;
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y1 = lines[j].y;
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x2 = lines[j].w;
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y2 = lines[j].h;
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if (SDL_IntersectRectAndLine(&r, &x1, &y1, &x2, &y2)) {
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SDL_SetRenderDrawColor(0, 255, 55, 255);
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SDL_RenderLine(x1, y1, x2, y2);
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}
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}
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SDL_SetRenderDrawBlendMode(SDL_BLENDMODE_NONE);
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}
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static void
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DrawRectRectIntersections(SDL_WindowID window)
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{
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int i, j;
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SDL_SetRenderDrawBlendMode(SDL_BLENDMODE_NONE);
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for (i = 0; i < num_rects; i++)
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for (j = i+1; j < num_rects; j++) {
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SDL_Rect r;
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if (SDL_IntersectRect(&rects[i], &rects[j], &r)) {
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SDL_SetRenderDrawColor(255, 200, 0, 255);
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SDL_RenderFill(&r);
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}
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}
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SDL_SetRenderDrawBlendMode(SDL_BLENDMODE_NONE);
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}
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int
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main(int argc, char *argv[])
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{
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int mouse_begin_x = -1, mouse_begin_y = -1;
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int i, done;
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SDL_Event event;
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Uint32 then, now, frames;
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/* Initialize parameters */
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num_objects = NUM_OBJECTS;
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/* Initialize test framework */
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state = CommonCreateState(argv, SDL_INIT_VIDEO);
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if (!state) {
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return 1;
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}
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for (i = 1; i < argc;) {
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int consumed;
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consumed = CommonArg(state, i);
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if (consumed == 0) {
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consumed = -1;
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if (SDL_strcasecmp(argv[i], "--blend") == 0) {
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if (argv[i + 1]) {
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if (SDL_strcasecmp(argv[i + 1], "none") == 0) {
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blendMode = SDL_BLENDMODE_NONE;
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consumed = 2;
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} else if (SDL_strcasecmp(argv[i + 1], "mask") == 0) {
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blendMode = SDL_BLENDMODE_MASK;
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consumed = 2;
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} else if (SDL_strcasecmp(argv[i + 1], "blend") == 0) {
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blendMode = SDL_BLENDMODE_BLEND;
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consumed = 2;
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} else if (SDL_strcasecmp(argv[i + 1], "add") == 0) {
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blendMode = SDL_BLENDMODE_ADD;
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consumed = 2;
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} else if (SDL_strcasecmp(argv[i + 1], "mod") == 0) {
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blendMode = SDL_BLENDMODE_MOD;
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consumed = 2;
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}
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}
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} else if (SDL_strcasecmp(argv[i], "--cyclecolor") == 0) {
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cycle_color = SDL_TRUE;
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consumed = 1;
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} else if (SDL_strcasecmp(argv[i], "--cyclealpha") == 0) {
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cycle_alpha = SDL_TRUE;
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consumed = 1;
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} else if (SDL_isdigit(*argv[i])) {
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num_objects = SDL_atoi(argv[i]);
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consumed = 1;
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}
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}
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if (consumed < 0) {
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fprintf(stderr,
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"Usage: %s %s [--blend none|mask|blend|add|mod] [--cyclecolor] [--cyclealpha]\n",
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argv[0], CommonUsage(state));
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return 1;
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}
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i += consumed;
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}
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if (!CommonInit(state)) {
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return 2;
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}
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/* Create the windows and initialize the renderers */
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for (i = 0; i < state->num_windows; ++i) {
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SDL_SelectRenderer(state->windows[i]);
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SDL_SetRenderDrawColor(0xA0, 0xA0, 0xA0, 0xFF);
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SDL_RenderFill(NULL);
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}
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srand(time(NULL));
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/* Main render loop */
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frames = 0;
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then = SDL_GetTicks();
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done = 0;
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while (!done) {
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/* Check for events */
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++frames;
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while (SDL_PollEvent(&event)) {
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CommonEvent(state, &event, &done);
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switch (event.type) {
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case SDL_MOUSEBUTTONDOWN:
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if (event.button.which == 0) {
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mouse_begin_x = event.button.x;
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mouse_begin_y = event.button.y;
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}
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break;
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case SDL_MOUSEBUTTONUP:
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if (event.button.which == 0) {
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if (event.button.button == 3)
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add_line(mouse_begin_x, mouse_begin_y, event.button.x, event.button.y);
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if (event.button.button == 1)
|
||||
add_rect(mouse_begin_x, mouse_begin_y, event.button.x, event.button.y);
|
||||
}
|
||||
break;
|
||||
case SDL_KEYDOWN:
|
||||
switch (event.key.keysym.sym) {
|
||||
case 'l':
|
||||
if (event.key.keysym.mod & KMOD_SHIFT) num_lines = 0;
|
||||
else add_line(rand()%640, rand()%480, rand()%640, rand()%480);
|
||||
break;
|
||||
case 'r':
|
||||
if (event.key.keysym.mod & KMOD_SHIFT) num_rects = 0;
|
||||
else add_rect(rand()%640, rand()%480, rand()%640, rand()%480);
|
||||
break;
|
||||
}
|
||||
break;
|
||||
case SDL_WINDOWEVENT:
|
||||
switch (event.window.event) {
|
||||
case SDL_WINDOWEVENT_EXPOSED:
|
||||
SDL_SelectRenderer(event.window.windowID);
|
||||
SDL_SetRenderDrawColor(0xA0, 0xA0, 0xA0, 0xFF);
|
||||
SDL_RenderFill(NULL);
|
||||
break;
|
||||
}
|
||||
break;
|
||||
default:
|
||||
break;
|
||||
}
|
||||
}
|
||||
for (i = 0; i < state->num_windows; ++i) {
|
||||
SDL_SelectRenderer(state->windows[i]);
|
||||
SDL_SetRenderDrawColor(0xA0, 0xA0, 0xA0, 0xFF);
|
||||
SDL_RenderFill(NULL);
|
||||
|
||||
DrawRects(state->windows[i]);
|
||||
DrawPoints(state->windows[i]);
|
||||
DrawRectRectIntersections(state->windows[i]);
|
||||
DrawLines(state->windows[i]);
|
||||
DrawRectLineIntersections(state->windows[i]);
|
||||
|
||||
SDL_RenderPresent();
|
||||
}
|
||||
}
|
||||
|
||||
/* Print out some timing information */
|
||||
now = SDL_GetTicks();
|
||||
if (now > then) {
|
||||
double fps = ((double) frames * 1000) / (now - then);
|
||||
printf("%2.2f frames per second\n", fps);
|
||||
}
|
||||
return 0;
|
||||
}
|
||||
|
||||
/* vi: set ts=4 sw=4 expandtab: */
|
||||
Loading…
Add table
Add a link
Reference in a new issue