sdl_rotozoom.c

国外一套很好的游戏代码,款经典的小游戏 希望大家提出宝贵意见 让我们一起进步

/*  

  SDL_rotozoom.c - rotozoomer for 32bit or 8bit surfaces

  LGPL (c) A. Schiffler

*/

#ifdef WIN32
#include <windows.h>
#endif

#include <stdlib.h>
#include <string.h>

#include "SDL_rotozoom.h"

#define MAX(a,b)    (((a) > (b)) ? (a) : (b))

/* 
 
 32bit Zoomer with optional anti-aliasing by bilinear interpolation.

 Zoomes 32bit RGBA/ABGR 'src' surface to 'dst' surface.
 
*/

int zoomSurfaceRGBA(SDL_Surface * src, SDL_Surface * dst, int smooth)
{
    int x, y, sx, sy, *sax, *say, *csax, *csay, csx, csy, ex, ey, t1, t2, sstep;
    tColorRGBA *c00, *c01, *c10, *c11;
    tColorRGBA *sp, *csp, *dp;
    int sgap, dgap;

    /*
     * Variable setup 
     */
    if (smooth) {
	/*
	 * For interpolation: assume source dimension is one pixel 
	 */
	/*
	 * smaller to avoid overflow on right and bottom edge.     
	 */
	sx = (int) (65536.0 * (float) (src->w - 1) / (float) dst->w);
	sy = (int) (65536.0 * (float) (src->h - 1) / (float) dst->h);
    } else {
	sx = (int) (65536.0 * (float) src->w / (float) dst->w);
	sy = (int) (65536.0 * (float) src->h / (float) dst->h);
    }

    /*
     * Allocate memory for row increments 
     */
    if ((sax = (int *) malloc((dst->w + 1) * sizeof(Uint32))) == NULL) {
	return (-1);
    }
    if ((say = (int *) malloc((dst->h + 1) * sizeof(Uint32))) == NULL) {
	free(sax);
	return (-1);
    }

    /*
     * Precalculate row increments 
     */
    csx = 0;
    csax = sax;
    for (x = 0; x <= dst->w; x++) {
	*csax = csx;
	csax++;
	csx &= 0xffff;
	csx += sx;
    }
    csy = 0;
    csay = say;
    for (y = 0; y <= dst->h; y++) {
	*csay = csy;
	csay++;
	csy &= 0xffff;
	csy += sy;
    }

    /*
     * Pointer setup 
     */
    sp = csp = (tColorRGBA *) src->pixels;
    dp = (tColorRGBA *) dst->pixels;
    sgap = src->pitch - src->w * 4;
    dgap = dst->pitch - dst->w * 4;

    /*
     * Switch between interpolating and non-interpolating code 
     */
    if (smooth) {

	/*
	 * Interpolating Zoom 
	 */

	/*
	 * Scan destination 
	 */
	csay = say;
	for (y = 0; y < dst->h; y++) {
	    /*
	     * Setup color source pointers 
	     */
	    c00 = csp;
	    c01 = csp;
	    c01++;
	    c10 = (tColorRGBA *) ((Uint8 *) csp + src->pitch);
	    c11 = c10;
	    c11++;
	    csax = sax;
	    for (x = 0; x < dst->w; x++) {

		/*
		 * Interpolate colors 
		 */
		ex = (*csax & 0xffff);
		ey = (*csay & 0xffff);
		t1 = ((((c01->r - c00->r) * ex) >> 16) + c00->r) & 0xff;
		t2 = ((((c11->r - c10->r) * ex) >> 16) + c10->r) & 0xff;
		dp->r = (((t2 - t1) * ey) >> 16) + t1;
		t1 = ((((c01->g - c00->g) * ex) >> 16) + c00->g) & 0xff;
		t2 = ((((c11->g - c10->g) * ex) >> 16) + c10->g) & 0xff;
		dp->g = (((t2 - t1) * ey) >> 16) + t1;
		t1 = ((((c01->b - c00->b) * ex) >> 16) + c00->b) & 0xff;
		t2 = ((((c11->b - c10->b) * ex) >> 16) + c10->b) & 0xff;
		dp->b = (((t2 - t1) * ey) >> 16) + t1;
		t1 = ((((c01->a - c00->a) * ex) >> 16) + c00->a) & 0xff;
		t2 = ((((c11->a - c10->a) * ex) >> 16) + c10->a) & 0xff;
		dp->a = (((t2 - t1) * ey) >> 16) + t1;

		/*
		 * Advance source pointers 
		 */
		csax++;
		sstep = (*csax >> 16);
		c00 += sstep;
		c01 += sstep;
		c10 += sstep;
		c11 += sstep;
		/*
		 * Advance destination pointer 
		 */
		dp++;
	    }
	    /*
	     * Advance source pointer 
	     */
	    csay++;
	    csp = (tColorRGBA *) ((Uint8 *) csp + (*csay >> 16) * src->pitch);
	    /*
	     * Advance destination pointers 
	     */
	    dp = (tColorRGBA *) ((Uint8 *) dp + dgap);
	}

    } else {

	/*
	 * Non-Interpolating Zoom 
	 */

	csay = say;
	for (y = 0; y < dst->h; y++) {
	    sp = csp;
	    csax = sax;
	    for (x = 0; x < dst->w; x++) {
		/*
		 * Draw 
		 */
		*dp = *sp;
		/*
		 * Advance source pointers 
		 */
		csax++;
		sp += (*csax >> 16);
		/*
		 * Advance destination pointer 
		 */
		dp++;
	    }
	    /*
	     * Advance source pointer 
	     */
	    csay++;
	    csp = (tColorRGBA *) ((Uint8 *) csp + (*csay >> 16) * src->pitch);
	    /*
	     * Advance destination pointers 
	     */
	    dp = (tColorRGBA *) ((Uint8 *) dp + dgap);
	}

    }

    /*
     * Remove temp arrays 
     */
    free(sax);
    free(say);

    return (0);
}

/* 
 
 8bit Zoomer without smoothing.

 Zoomes 8bit palette/Y 'src' surface to 'dst' surface.
 
*/

int zoomSurfaceY(SDL_Surface * src, SDL_Surface * dst)
{
    Uint32 x, y, sx, sy, *sax, *say, *csax, *csay, csx, csy;
    Uint8 *sp, *dp, *csp;
    int dgap;

    /*
     * Variable setup 
     */
    sx = (Uint32) (65536.0 * (float) src->w / (float) dst->w);
    sy = (Uint32) (65536.0 * (float) src->h / (float) dst->h);

    /*
     * Allocate memory for row increments 
     */
    if ((sax = (Uint32 *) malloc(dst->w * sizeof(Uint32))) == NULL) {
	return (-1);
    }
    if ((say = (Uint32 *) malloc(dst->h * sizeof(Uint32))) == NULL) {
	if (sax != NULL) {
	    free(sax);
	}
	return (-1);
    }

    /*
     * Precalculate row increments 
     */
    csx = 0;
    csax = sax;
    for (x = 0; x < dst->w; x++) {
	csx += sx;
	*csax = (csx >> 16);
	csx &= 0xffff;
	csax++;
    }
    csy = 0;
    csay = say;
    for (y = 0; y < dst->h; y++) {
	csy += sy;
	*csay = (csy >> 16);
	csy &= 0xffff;
	csay++;
    }

    csx = 0;
    csax = sax;
    for (x = 0; x < dst->w; x++) {
	csx += (*csax);
	csax++;
    }
    csy = 0;
    csay = say;
    for (y = 0; y < dst->h; y++) {
	csy += (*csay);
	csay++;
    }

    /*
     * Pointer setup 
     */
    sp = csp = (Uint8 *) src->pixels;
    dp = (Uint8 *) dst->pixels;
    dgap = dst->pitch - dst->w;

    /*
     * Draw 
     */
    csay = say;
    for (y = 0; y < dst->h; y++) {
	csax = sax;
	sp = csp;
	for (x = 0; x < dst->w; x++) {
	    /*
	     * Draw 
	     */
	    *dp = *sp;
	    /*
	     * Advance source pointers 
	     */
	    sp += (*csax);
	    csax++;
	    /*
	     * Advance destination pointer 
	     */
	    dp++;
	}
	/*
	 * Advance source pointer (for row) 
	 */
	csp += ((*csay) * src->pitch);
	csay++;
	/*
	 * Advance destination pointers 
	 */
	dp += dgap;
    }

    /*
     * Remove temp arrays 
     */
    free(sax);
    free(say);

    return (0);
}

/* 
 
 32bit Rotozoomer with optional anti-aliasing by bilinear interpolation.

 Rotates and zoomes 32bit RGBA/ABGR 'src' surface to 'dst' surface.
 
*/

void transformSurfaceRGBA(SDL_Surface * src, SDL_Surface * dst, int cx, int cy, int isin, int icos, int smooth)
{
    int x, y, t1, t2, dx, dy, xd, yd, sdx, sdy, ax, ay, ex, ey, sw, sh;
    tColorRGBA c00, c01, c10, c11;
    tColorRGBA *pc, *sp;
    int gap;

    /*
     * Variable setup 
     */
    xd = ((src->w - dst->w) << 15);
    yd = ((src->h - dst->h) << 15);
    ax = (cx << 16) - (icos * cx);
    ay = (cy << 16) - (isin * cx);
    sw = src->w - 1;
    sh = src->h - 1;
    pc = dst->pixels;
    gap = dst->pitch - dst->w * 4;

    /*
     * Switch between interpolating and non-interpolating code 
     */
    if (smooth) {
	for (y = 0; y < dst->h; y++) {
	    dy = cy - y;
	    sdx = (ax + (isin * dy)) + xd;
	    sdy = (ay - (icos * dy)) + yd;
	    for (x = 0; x < dst->w; x++) {
		dx = (sdx >> 16);
		dy = (sdy >> 16);
		if ((dx >= -1) && (dy >= -1) && (dx < src->w) && (dy < src->h)) {
		    if ((dx >= 0) && (dy >= 0) && (dx < sw) && (dy < sh)) {
			sp = (tColorRGBA *) ((Uint8 *) src->pixels + src->pitch * dy);
			sp += dx;
			c00 = *sp;
			sp += 1;
			c01 = *sp;
			sp = (tColorRGBA *) ((Uint8 *) sp + src->pitch);
			sp -= 1;
			c10 = *sp;
			sp += 1;
			c11 = *sp;
		    } else if ((dx == sw) && (dy == sh)) {
			sp = (tColorRGBA *) ((Uint8 *) src->pixels + src->pitch * dy);
			sp += dx;
			c00 = *sp;
			c01 = *sp;
			c10 = *sp;
			c11 = *sp;
		    } else if ((dx == -1) && (dy == -1)) {
			sp = (tColorRGBA *) (src->pixels);
			c00 = *sp;
			c01 = *sp;
			c10 = *sp;
			c11 = *sp;
		    } else if ((dx == -1) && (dy == sh)) {
			sp = (tColorRGBA *) (src->pixels);
			sp = (tColorRGBA *) ((Uint8 *) src->pixels + src->pitch * dy);
			c00 = *sp;
			c01 = *sp;
			c10 = *sp;
			c11 = *sp;
		    } else if ((dx == sw) && (dy == -1)) {
			sp = (tColorRGBA *) (src->pixels);
			sp += dx;
			c00 = *sp;
			c01 = *sp;
			c10 = *sp;
			c11 = *sp;
		    } else if (dx == -1) {
			sp = (tColorRGBA *) ((Uint8 *) src->pixels + src->pitch * dy);
			c00 = *sp;
			c01 = *sp;
			c10 = *sp;
			sp = (tColorRGBA *) ((Uint8 *) sp + src->pitch);
			c11 = *sp;
		    } else if (dy == -1) {
			sp = (tColorRGBA *) (src->pixels);
			sp += dx;
			c00 = *sp;
			c01 = *sp;
			c10 = *sp;
			sp += 1;
			c11 = *sp;
		    } else if (dx == sw) {
			sp = (tColorRGBA *) ((Uint8 *) src->pixels + src->pitch * dy);
			sp += dx;
			c00 = *sp;
			c01 = *sp;
			sp = (tColorRGBA *) ((Uint8 *) sp + src->pitch);
			c10 = *sp;
			c11 = *sp;
		    } else if (dy == sh) {
			sp = (tColorRGBA *) ((Uint8 *) src->pixels + src->pitch * dy);
			sp += dx;
			c00 = *sp;
			sp += 1;
			c01 = *sp;
			c10 = *sp;
			c11 = *sp;
		    }
		    /*
		     * Interpolate colors 
		     */
		    ex = (sdx & 0xffff);
		    ey = (sdy & 0xffff);
		    t1 = ((((c01.r - c00.r) * ex) >> 16) + c00.r) & 0xff;
		    t2 = ((((c11.r - c10.r) * ex) >> 16) + c10.r) & 0xff;
		    pc->r = (((t2 - t1) * ey) >> 16) + t1;
		    t1 = ((((c01.g - c00.g) * ex) >> 16) + c00.g) & 0xff;
		    t2 = ((((c11.g - c10.g) * ex) >> 16) + c10.g) & 0xff;
		    pc->g = (((t2 - t1) * ey) >> 16) + t1;
		    t1 = ((((c01.b - c00.b) * ex) >> 16) + c00.b) & 0xff;
		    t2 = ((((c11.b - c10.b) * ex) >> 16) + c10.b) & 0xff;
		    pc->b = (((t2 - t1) * ey) >> 16) + t1;
		    t1 = ((((c01.a - c00.a) * ex) >> 16) + c00.a) & 0xff;
		    t2 = ((((c11.a - c10.a) * ex) >> 16) + c10.a) & 0xff;
		    pc->a = (((t2 - t1) * ey) >> 16) + t1;
		}
		sdx += icos;
		sdy += isin;
		pc++;
	    }
	    pc = (tColorRGBA *) ((Uint8 *) pc + gap);
	}
    } else {
	for (y = 0; y < dst->h; y++) {
	    dy = cy - y;
	    sdx = (ax + (isin * dy)) + xd;
	    sdy = (ay - (icos * dy)) + yd;
	    for (x = 0; x < dst->w; x++) {
		dx = (short) (sdx >> 16);
		dy = (short) (sdy >> 16);
		if ((dx >= 0) && (dy >= 0) && (dx < src->w) && (dy < src->h)) {
		    sp = (tColorRGBA *) ((Uint8 *) src->pixels + src->pitch * dy);
		    sp += dx;
		    *pc = *sp;
		}
		sdx += icos;
		sdy += isin;
		pc++;