我正在尝试在我的mandelbrot代码中实现放大/缩小功能。我部分实现了缩放功能，但在放大时，它变得模糊，无法再看到mandelbrot设置了..
这是我的代码......
// menu constants
#define MANDELBROT 0 // set
#define JULIA 1
#define ITERATIONS 2 // method
#define MAGNITUDE 3
#define REAL 4
#define IMAGINARY 5
#define RED 6 // color
#define YELLOW 7
#define GREEN 8
#define CYAN 9
#define BLUE 10
#define MAGENTA 11
#define WHITE 12
#define QUIT 13
#define ZOOM 14 // zoom
#define ZOOM_IN 15 // zoom in
#define ZOOM_OUT 16 // zoom out
#define KEY_ESC 27 /* ascii value for the escape key */
int set = MANDELBROT;
int nx, ny, imax=60, method=ITERATIONS, color=RED, hue=0, zoom = 1;
double x0=-0.5, y0a=0, dpi, power=2, xc=0.5, yc=0.05;
int ok=0;
double x1=-2.5, x2=1.5, y1f=-2, y2=2, zx, zy, ***screen;
double abs2(double x) {return (x>0)?x:(-x);}
double min(double x1, double x2) {return (x1<x2)?x1:x2;}
double max(double x1, double x2) {return (x1>x2)?x1:x2;}
double rem(double x1, double x2) {return x1-x2*(int)(x1/x2);}
void pixel(int x, int y, int r, int g, int b) {
glColor3f(r/256.0, g/256.0, b/256.0);
glVertex2i(x, y);
}
GLdouble xmin = -1.5, xmax = +1; /* edges of world "window" */
GLdouble ymin = -1.25, ymax = +1.25;
GLint viewportWidth, viewportHeight; /* size of "viewport" */
void reshape(int w, int h) {
glViewport(0,0, w,h);
viewportWidth = w;
viewportHeight = h;
}
#define NUM_COLORS 1000
static GLfloat colorMap[NUM_COLORS+1][3];
void initColorMap(void) {
GLfloat gray, dgray = 1.0/NUM_COLORS;
int i;
for (i = 0, gray = 1.0; i < NUM_COLORS; i++, gray -= dgray) {
colorMap[i][0] = gray;
colorMap[i][1] = gray*gray;
colorMap[i][2] = gray*gray*gray;
}
}
int escapeDistance(GLdouble x, GLdouble y, int maxDist) {
int iters = 0;
GLdouble a = x, b = y;
while (a*a + b*b < 2*2 && iters < maxDist) {
GLdouble a_old = a;
a = a*a - b*b + x;
b = 2*a_old*b + y;
iters++;
}
return iters;;
}
#define DETAILED_QUAD_SIZE 1
#define FAST_QUAD_SIZE 10
#define DETAILED_ITERS 1000
#define FAST_ITERS 1000
void mandelbrot(int quadSize, int maxIters) {
int W = viewportWidth/quadSize;
int H = viewportHeight/quadSize;
GLdouble dx = (xmax - xmin)/(W-1);
GLdouble dy = (ymax - ymin)/(H-1);
GLdouble x,y;
int r, c;
for (r = 0, y = ymax; r < H; r++, y -= dy) {
glBegin(GL_QUAD_STRIP);
for (c = 0, x = xmin; c < W; c++, x += dx) {
int dist = escapeDistance(x,y, maxIters);
glColor3fv(colorMap[dist*NUM_COLORS/maxIters]);
glVertex2d(x,y);
dist = escapeDistance(x,y-dy, maxIters);
glColor3fv(colorMap[dist*NUM_COLORS/maxIters]);
glVertex2d(x,y-dy);
}
glEnd();
}
}
GLboolean fastDraw = GL_FALSE;
void display(void) {
int unbounded = 0;
int r=0, g=0, b=0, i, n=(int)power/2-((rem(power,2)!=0)?1:0);
double x=0, y=0, xc1=xc, yc1=yc, dx=1/(dpi), x1=x0-0.5*nx/(dpi), x2=x0+0.5*nx/dpi, y1a=y0a-ny*dx/2, y2=y0a+ny*dx/2;
double t1=max(abs2(x1),abs2(x2)), t2=max(abs2(y1a),abs2(y2)), zm=sqrt(t1*t1+t2*t2);
int iy,ix,j; // supposed to go in for loop
double r1, g1, b1;
//char txt[100];
switch(color) { // calculations
case RED: hue=0 ; break;
case YELLOW: hue=60 ; break;
case GREEN: hue=120; break;
case CYAN: hue=180; break;
case BLUE: hue=240; break;
case MAGENTA: hue=300; break;
}
r1=max(0,min(1,abs2(rem(6-hue/60.0,6)-3)-1));
g1=max(0,min(1,abs2(rem(8-hue/60.0,6)-3)-1));
b1=max(0,min(1,abs2(rem(10-hue/60.0,6)-3)-1));
glClear(GL_COLOR_BUFFER_BIT);
glBegin(GL_POINTS);
for (iy=0; iy<=ny; ++iy) {
if (set==MANDELBROT) yc1=y2-iy*dx;
for (ix=0; ix<=nx; ++ix) {
if (set==JULIA) {x=x1+ix*dx; y=y2-iy*dx;} else {xc1=x1+ix*dx; x=0; y=0;}
unbounded=0;
for (i=0; (i<imax)&&(!unbounded); ++i) {
if (power>=2 && power<=25 && rem(power,1)==0) {
for (j=0; j<n; ++j) {t1=x*x-y*y; y=2*x*y; x=t1;}; // z^2
if (rem(power,2)!=0) {t1=x*(x*x-3*y*y); y=y*(3*x*x-y*y); x=t1;} // z^3
}
else {t1= atan2(y,x); t2= pow(x*x+y*y,power/2.0); x=t2* cos(power*t1); y=t2* sin(power*t1);} // z^n
x+=xc1; y+=yc1;
if (x*x+y*y>=4.0) unbounded=1;
}
if (unbounded) {
if (method==ITERATIONS) t1=1.0*i/imax;
else if (method==MAGNITUDE) t1= min(1, sqrt(x*x+y*y)/zm);
else t1= min(1, abs2((method==REAL)?x:y)/zm);
if (color==WHITE) {r=255*t1; g=r; b=r;}
else { // Note: brightness=(int)t1*100;
r = 255*((t1>0.5)?t1*r1+(1-t1*r1)*(2*t1-1):2*t1*r1);
g = 255*((t1>0.5)?t1*g1+(1-t1*g1)*(2*t1-1):2*t1*g1);
b = 255*((t1>0.5)?t1*b1+(1-t1*b1)*(2*t1-1):2*t1*b1);
}
pixel(ix,iy,r,g,b);
}
}
}
glEnd();
glColor3f(1,1,1);
//sprintf(txt, "%s Set: %f", (set == JULIA) ? "Julia" : "Mandelbrot", t1);
//text(10, 10, txt);
glutSwapBuffers();
}
GLboolean dragMouse = GL_FALSE; /* currently dragging mouse? */
GLboolean zoomMouse = GL_FALSE; /* currently zoom mouse? */
int mousex, mousey; /* last mouse position during drag */
void mouse(int button, int state, int x, int y) {
if (state == GLUT_DOWN ) {
if (button == GLUT_LEFT_BUTTON) {
dragMouse = fastDraw = GL_TRUE;
glutSetCursor(GLUT_CURSOR_CROSSHAIR);
mousex = x;
mousey = y;
} else if (button == GLUT_RIGHT_BUTTON) {
zoomMouse = fastDraw = GL_TRUE;
glutSetCursor(GLUT_CURSOR_UP_DOWN);
mousey = y;
}
} else if (state == GLUT_UP && (dragMouse || zoomMouse)) {
dragMouse = zoomMouse = fastDraw = GL_FALSE;
glutPostRedisplay(); /* request a redisplay */
}
}
#define UNITS_PER_PIXEL 0.01 /* translation per pixel at zoom scale = 1.0 */
GLdouble unitsPerPixel = UNITS_PER_PIXEL;
GLdouble zoomsPerPixel = 1.0/100; /* scale = exp(z*zoomsPerPixel) */
void mouseMotion(int x, int y) {
if (dragMouse) {
GLdouble dx = (x - mousex)*unitsPerPixel;
GLdouble dy = (y - mousey)*unitsPerPixel;
xmin -= dx;
xmax -= dx;
ymin += dy;
ymax += dy;
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(xmin, xmax, ymin, ymax, -1,+1);
mousex = x;
mousey = y;
glutPostRedisplay(); /* request a redisplay */
} else if (zoomMouse) {
GLdouble scale = exp((y - mousey)*zoomsPerPixel);
GLdouble cx = 0.5*(xmin + xmax);
GLdouble cy = 0.5*(ymin + ymax);
xmin = (xmin - cx)*scale + cx;
xmax = (xmax - cx)*scale + cx;
ymin = (ymin - cy)*scale + cy;
ymax = (ymax - cy)*scale + cy;
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(xmin, xmax, ymin, ymax, -1,+1);
mousey = y;
unitsPerPixel *= scale;
glutPostRedisplay(); /* request a redisplay */
}
}
#define ESC 27
void keyboard(unsigned char key, int x, int y) {
if (key == ESC) exit(0);
}
int main(int argc, char *argv[]) {
nx=1200; ny=nx*3/4;
dpi=(nx/3);
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
glutInitWindowSize(nx, ny);
glutInitWindowPosition(550, 150);
glutCreateWindow("Mandelbrot");
gluOrtho2D(0, nx, 0, ny);
glutKeyboardFunc( keyboard );
glutMouseFunc(mouse);
glutMotionFunc(mouseMotion);
glutDisplayFunc(display);
glMatrixMode(GL_MODELVIEW);
glMatrixMode(GL_PROJECTION);
glClearColor(0, 0, 0, 1);
glutMainLoop();
return 0;
}
PS：这不是作业..
答案 0 :(得分：0)
你放大多远？即窗户角落的坐标是什么？
可能是你遇到了double类型的有限精度。请注意，有一些值DBL_EPSILON（在<float.h>中定义），这样当x＆lt; DBL_EPSILON 1 + x == 1。