English Amiga Board - View Single Post - Blitter fill, writing clearing instead of setting?

a/b · 16 December 2019, 19:04

OK, i see. Not a typical poly renderer.

Option 1:
Assuming you clear the entire bitplane beforehand, and the horizon is a simple straight line: find min_y and max_y (screen coords) of the plane while drawing sky/plane lines and then only fill between them.

Option 2:
How about a simple post-processing loop to clear bytes that are equal to 1 (only the rightmost pixel is set), something like:

Code:

char  table[256] = { 0, 0, 2, 3, 4, ..., 255 };  // 1 is mapped to 0, the rest is unchanged
char* p_plane = sky_plane_bitplane+width/8-1; // last byte of the first line
for (int h = 0;  h < height;  ++h)
  { *p_plane = table[*p_plane];  p_plane += width/8; }

16 December 2019, 19:04	#13
a/b Registered User Join Date: Jun 2016 Location: europe Posts: 1,039	OK, i see. Not a typical poly renderer. Option 1: Assuming you clear the entire bitplane beforehand, and the horizon is a simple straight line: find min_y and max_y (screen coords) of the plane while drawing sky/plane lines and then only fill between them. Option 2: How about a simple post-processing loop to clear bytes that are equal to 1 (only the rightmost pixel is set), something like: Code: char table[256] = { 0, 0, 2, 3, 4, ..., 255 }; // 1 is mapped to 0, the rest is unchanged char* p_plane = sky_plane_bitplane+width/8-1; // last byte of the first line for (int h = 0; h < height; ++h) { p_plane = table[p_plane]; p_plane += width/8; }