vg4->image->attr_sum()

Sum two image-copy attributes.

SYNTAX

void vg4->image->attr_sum(struct VG_ImagecopyAttr *iattr_sum, const struct VG_ImagecopyAttr *iattr1, const struct VG_ImagecopyAttr *iattr2)

FUNCTION PARAMETERS

iattr_sum	For returning summed image-copy attributes
iattr1	Image-copy attributes to be summed
iattr2	Image-copy attributes to be summed

DESCRIPTION

Sum two image-copy attributes. Use this function if an image has image-copy attributes, e.g. from a sprite, and shall be copied with additional image-copy attributes.

EXAMPLE

/* copy image of a sprite with reduced brightness onto window */

struct VG_Sprite *sprt;
struct VG_Image *imgp;
struct VG_ImagecopyAttr iattr1, iattr2, iattr_sum;

/* load sprite, assuming no error */
sprt = vg4->sprite->load("my.sprite");

/* set attributes with reduced brightness */
VG_IMAGECOPY_ATTR_DEFAULT(&iattr1);
iattr1.pixel.brightness = 50;

/* get next image of sprite */
if (vg4->sprite->next(sprt, &imgp, &iattr2) && imgp != NULL) {
  /* sum reduced brightness with attributes from sprite-image */
  vg4->image->attr_sum(&iattr_sum, &iattr1, &iattr2);
  /* copy image onto window with calculated attributes */
  vg4->window->copy(imgp, NULL, &iattr_sum);
}