// Bresenham simple line drawing
void raster_rgba_line(pb_rgba *pb, unsigned int x1, unsigned int y1, unsigned int x2, unsigned int y2, uint32_t color)
{
int dx, dy;
int i;
int sdx, sdy, dxabs, dyabs;
unsigned int x, y, px, py;
dx = x2 - x1; /* the horizontal distance of the line */
dy = y2 - y1; /* the vertical distance of the line */
dxabs = abs(dx);
dyabs = abs(dy);
sdx = sgn(dx);
sdy = sgn(dy);
x = dyabs >> 1;
y = dxabs >> 1;
px = x1;
py = y1;
pb_rgba_set_pixel(pb, x1, y1, color);
if (dxabs >= dyabs) /* the line is more horizontal than vertical */
{
for (i = 0; i<dxabs; i++)
{
y += dyabs;
if (y >= (unsigned int)dxabs)
{
y -= dxabs;
py += sdy;
}
px += sdx;
pb_rgba_set_pixel(pb, px, py, color);
}
}
else /* the line is more vertical than horizontal */
{
for (i = 0; i<dyabs; i++)
{
x += dxabs;
if (x >= (unsigned int)dyabs)
{
x -= dyabs;
px += sdx;
}
py += sdy;
pb_rgba_set_pixel(pb, px, py, color);
}
}
}
void raster_rgba_vline_fade(pb_rgba *pb, int y1, uint32_t color1, int y2, uint32_t color2, int x)
{
int ydiff = y2 - y1;
if (ydiff == 0)
return;
int c1rd = GET_R(color1);
int c1gr = GET_G(color1);
int c1bl = GET_B(color1);
int c2rd = GET_R(color2);
int c2gr = GET_G(color2);
int c2bl = GET_B(color2);
int rdx = c2rd - c1rd;
int gdx = c2gr - c1gr;
int bdx = c2bl - c1bl;
float factor = 0.0f;
float factorStep = 1.0f / (float)ydiff;
// draw each pixel in the span
for (int y = y1; y < y2; y++) {
int rd = c1rd + (int)(rdx*factor);
int gr = c1gr + (int)(gdx*factor);
int bl = c1bl + (int)(bdx*factor);
int fg = RGBA(rd, gr, bl, 255);
pb_rgba_set_pixel(pb, x, y, fg);
factor += factorStep;
}
}
void pb_rgba_cover_pixel(pb_rgba *pb, const unsigned int x, const unsigned int y, const uint32_t value)
{
// Quick reject if the foreground pixel has both 0 opacity
// and 0 for color component values
if (0 == value) {
return;
}
if (0 == GET_A(value)) {
// Combine the colors, but don't
// change the alpha of the background
} else if (255 == GET_A(value)) {
// The foreground opacity is full, so set
// the color
// and set the background alpha to full as well
pb_rgba_set_pixel(pb, x, y, value);
} else {
// All other cases where doing a cover of something
// other than full opacity
uint8_t alpha = GET_A(value);
int32_t dstPixel = pb_rgba_get_pixel(pb, x, y);
int dstColor = RGBA(
lerp255(GET_R(dstPixel), GET_R(value), alpha),
lerp255(GET_G(dstPixel), GET_G(value), alpha),
lerp255(GET_B(dstPixel), GET_B(value), alpha),
lerp255(GET_A(dstPixel), GET_A(value), alpha)
);
pb_rgba_set_pixel(pb, x, y, dstColor);
/*
pix_rgba * B = (pix_rgba *)&pb->data[(y*(pb)->pixelpitch) + x];
B->r = lerp255(B->r, GET_R(value), alpha);
B->g = lerp255(B->g, GET_R(value), alpha);
B->b = lerp255(B->b, GET_R(value), alpha);
B->a = lerp255(B->a, GET_R(value), alpha);
*/
}
}
