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Macros
#define	MIN(a, b) (((a) < (b)) ? (a) : (b))

Functions
SDL_Surface *	SDLgfx_rotateSurface (SDL_Surface *src, double angle, int centerx, int centery, int smooth, int flipx, int flipy, int dstwidth, int dstheight, double cangle, double sangle)
void	SDLgfx_rotozoomSurfaceSizeTrig (int width, int height, double angle, int dstwidth, int dstheight, double cangle, double sangle)

Macro Definition Documentation

#define MIN	(	a,
		b
	)	(((a) < (b)) ? (a) : (b))

Definition at line 26 of file SDL_rotate.h.

Referenced by SW_RenderCopyEx().

Function Documentation

SDL_Surface* SDLgfx_rotateSurface	(	SDL_Surface *	src,
		double	angle,
		int	centerx,
		int	centery,
		int	smooth,
		int	flipx,
		int	flipy,
		int	dstwidth,
		int	dstheight,
		double	cangle,
		double	sangle
	)

Definition at line 415 of file SDL_rotate.c.

References _transformSurfaceRGBA(), SDL_PixelFormat::Amask, SDL_PixelFormat::BitsPerPixel, SDL_PixelFormat::Bmask, SDL_Palette::colors, SDL_Surface::format, SDL_PixelFormat::Gmask, GUARD_ROWS, SDL_Surface::h, i, SDL_Palette::ncolors, NULL, SDL_PixelFormat::palette, SDL_PixelFormat::Rmask, SDL_BLENDMODE_BLEND, SDL_BLENDMODE_MOD, SDL_BLENDMODE_NONE, SDL_CreateRGBSurface, SDL_FALSE, SDL_FillRect, SDL_GetColorKey, SDL_GetSurfaceBlendMode, SDL_HasColorKey, SDL_LockSurface, SDL_MapRGBA, SDL_MUSTLOCK, SDL_SetColorKey, SDL_SetSurfaceBlendMode, SDL_TRUE, SDL_UnlockSurface, transformSurfaceRGBA90(), transformSurfaceY(), and transformSurfaceY90().

Referenced by SW_RenderCopyEx().

{
    SDL_Surface *rz_dst;
    int is8bit, angle90;
    int i;
    SDL_BlendMode blendmode;
    Uint32 colorkey = 0;
    int colorKeyAvailable = SDL_FALSE;
    double sangleinv, cangleinv;
    /* Sanity check */
    if (src == NULL)
        return NULL;
    if (SDL_HasColorKey(src)) {
        if (SDL_GetColorKey(src, &colorkey) == 0) {
            colorKeyAvailable = SDL_TRUE;
        }
    }
    /* This function requires a 32-bit surface or 8-bit surface with a colorkey */
    is8bit = src->format->BitsPerPixel == 8 && colorKeyAvailable;
    if (!(is8bit || (src->format->BitsPerPixel == 32 && src->format->Amask)))
        return NULL;
    /* Calculate target factors from sin/cos and zoom */
    sangleinv = sangle*65536.0;
    cangleinv = cangle*65536.0;
    /* Alloc space to completely contain the rotated surface */
    rz_dst = NULL;
    if (is8bit) {
        /* Target surface is 8 bit */
        rz_dst = SDL_CreateRGBSurface(0, dstwidth, dstheight + GUARD_ROWS, 8, 0, 0, 0, 0);
        if (rz_dst != NULL) {
            for (i = 0; i < src->format->palette->ncolors; i++) {
                rz_dst->format->palette->colors[i] = src->format->palette->colors[i];
            }
            rz_dst->format->palette->ncolors = src->format->palette->ncolors;
        }
    } else {
        /* Target surface is 32 bit with source RGBA ordering */
        rz_dst = SDL_CreateRGBSurface(0, dstwidth, dstheight + GUARD_ROWS, 32,
                                      src->format->Rmask, src->format->Gmask,
                                      src->format->Bmask, src->format->Amask);
    }
    /* Check target */
    if (rz_dst == NULL)
        return NULL;
    /* Adjust for guard rows */
    rz_dst->h = dstheight;
    SDL_GetSurfaceBlendMode(src, &blendmode);
    if (colorKeyAvailable == SDL_TRUE) {
        /* If available, the colorkey will be used to discard the pixels that are outside of the rotated area. */
        SDL_SetColorKey(rz_dst, SDL_TRUE, colorkey);
        SDL_FillRect(rz_dst, NULL, colorkey);
    } else if (blendmode == SDL_BLENDMODE_NONE) {
        blendmode = SDL_BLENDMODE_BLEND;
    } else if (blendmode == SDL_BLENDMODE_MOD) {
        /* Without a colorkey, the target texture has to be white for the MOD blend mode so
         * that the pixels outside the rotated area don't affect the destination surface.
         */
        colorkey = SDL_MapRGBA(rz_dst->format, 255, 255, 255, 0);
        SDL_FillRect(rz_dst, NULL, colorkey);
        /* Setting a white colorkey for the destination surface makes the final blit discard
         * all pixels outside of the rotated area. This doesn't interfere with anything because
         * white pixels are already a no-op and the MOD blend mode does not interact with alpha.
         */
        SDL_SetColorKey(rz_dst, SDL_TRUE, colorkey);
    }
    SDL_SetSurfaceBlendMode(rz_dst, blendmode);
    /* Lock source surface */
    if (SDL_MUSTLOCK(src)) {
        SDL_LockSurface(src);
    }
    /* check if the rotation is a multiple of 90 degrees so we can take a fast path and also somewhat reduce
     * the off-by-one problem in _transformSurfaceRGBA that expresses itself when the rotation is near
     * multiples of 90 degrees.
     */
    angle90 = (int)(angle/90);
    if (angle90 == angle/90) {
        angle90 %= 4;
        if (angle90 < 0) angle90 += 4; /* 0:0 deg, 1:90 deg, 2:180 deg, 3:270 deg */
    } else {
        angle90 = -1;
    }
    if (is8bit) {
        /* Call the 8-bit transformation routine to do the rotation */
        if(angle90 >= 0) {
            transformSurfaceY90(src, rz_dst, angle90, flipx, flipy);
        } else {
            transformSurfaceY(src, rz_dst, centerx, centery, (int)sangleinv, (int)cangleinv,
                              flipx, flipy);
        }
    } else {
        /* Call the 32-bit transformation routine to do the rotation */
        if (angle90 >= 0) {
            transformSurfaceRGBA90(src, rz_dst, angle90, flipx, flipy);
        } else {
            _transformSurfaceRGBA(src, rz_dst, centerx, centery, (int)sangleinv, (int)cangleinv,
                                  flipx, flipy, smooth);
        }
    }
    /* Unlock source surface */
    if (SDL_MUSTLOCK(src)) {
        SDL_UnlockSurface(src);
    }
    /* Return rotated surface */
    return rz_dst;
}

void SDLgfx_rotozoomSurfaceSizeTrig	(	int	width,
		int	height,
		double	angle,
		int *	dstwidth,
		int *	dstheight,
		double *	cangle,
		double *	sangle
	)

Definition at line 106 of file SDL_rotate.c.

References MAX, SDL_ceil, SDL_cos, SDL_fabs, and SDL_sin.

Referenced by SW_RenderCopyEx().

{
    /* The trig code below gets the wrong size (due to FP inaccuracy?) when angle is a multiple of 90 degrees */
    int angle90 = (int)(angle/90);
    if(angle90 == angle/90) { /* if the angle is a multiple of 90 degrees */
        angle90 %= 4;
        if(angle90 < 0) angle90 += 4; /* 0:0 deg, 1:90 deg, 2:180 deg, 3:270 deg */
        if(angle90 & 1) {
            *dstwidth  = height;
            *dstheight = width;
            *cangle = 0;
            *sangle = angle90 == 1 ? -1 : 1; /* reversed because our rotations are clockwise */
        } else {
            *dstwidth  = width;
            *dstheight = height;
            *cangle = angle90 == 0 ? 1 : -1;
            *sangle = 0;
        }
    } else {
        double x, y, cx, cy, sx, sy;
        double radangle;
        int dstwidthhalf, dstheighthalf;
        /*
        * Determine destination width and height by rotating a centered source box
        */
        radangle = angle * (M_PI / -180.0); /* reverse the angle because our rotations are clockwise */
        *sangle = SDL_sin(radangle);
        *cangle = SDL_cos(radangle);
        x = (double)(width / 2);
        y = (double)(height / 2);
        cx = *cangle * x;
        cy = *cangle * y;
        sx = *sangle * x;
        sy = *sangle * y;
        dstwidthhalf = MAX((int)
            SDL_ceil(MAX(MAX(MAX(SDL_fabs(cx + sy), SDL_fabs(cx - sy)), SDL_fabs(-cx + sy)), SDL_fabs(-cx - sy))), 1);
        dstheighthalf = MAX((int)
            SDL_ceil(MAX(MAX(MAX(SDL_fabs(sx + cy), SDL_fabs(sx - cy)), SDL_fabs(-sx + cy)), SDL_fabs(-sx - cy))), 1);
        *dstwidth = 2 * dstwidthhalf;
        *dstheight = 2 * dstheighthalf;
    }
}

Macros

Functions

Macro Definition Documentation

Function Documentation