Image processing and transparency

Image processing and transparency

zyklus_

Member #8,481

April 2007

I've been having problems when working with transparency when doing image processing...

The game consists of two boards (one for now). A board is a grid of 6x12 pieces, but 8x14 for padding. The pieces are connected when neighboring like pieces. The drawing process is done for each piece, on a temporary bitmap. Then it is mask_blitted onto the video. All BMP versions of the images are in 256 colors, I am also running the game in 32bit color.

1. Here is my game, no image processing: http://zyklus.acaro.org/host/puyo/debug00.jpg (boring)
2. This is the image map, and its mask: http://zyklus.acaro.org/host/puyo/debug05.jpg
The mask is green for a reason, it will be inverted later.
3. This is the board, showing neighbors: http://zyklus.acaro.org/host/puyo/debug01.jpg
4. Result of multiplying 1 with 3: http://zyklus.acaro.org/host/puyo/debug02.jpg (better, but need to fix that black area to be transparent)
5. This is the mask I want to use: http://zyklus.acaro.org/host/puyo/debug03.jpg (why is the magenta yellow?)
6. Invert 5 and mask_blit onto 4:
http://zyklus.acaro.org/host/puyo/debug04.jpg

I get the mask that I want, but it destroys everything else X|
Any ideas?

EDIT: here is some code:

1 
2#define TILE_GET_CONNECTORS(x)  (((x)&(15<<8))>>8)
3 
4struct v2 { float x, y; };
5typedef unsigned int word;
6typedef unsigned char byte;
7 
8.
9.
10.
11 
12void CBoard::DrawBlockProc( v2 &v, word tile )
13{
14  BITMAP *bmp = g_pGame->GetGfx()->GetRamPage();
15 // RamPage is a temporary ram bitmap for post-image processing... blitted onto video later.
16  byte n = 0, color = tile & 0xFF;
17 
18  // Draw the base:
19  if ( color == 0 ) // Empty space here, nothing to do
20    return;
21  if ( (--color) >= m_iNumberOfTileImages ) // If color is 1, it indexes tile_bitmap 0
22    rectfill( m_pBmpTemp, 0, 0, m_iBlocksz, m_iBlocksz, makecol( 64, 64, 64 ) );
23  else
24  {
25    n = TILE_GET_CONNECTORS(tile);
26    drawing_mode( DRAW_MODE_COPY_PATTERN, m_pBmpTileImgs[color], -v.x, -v.y );
27    rectfill( m_pBmpTemp, 0, 0, m_iBlocksz, m_iBlocksz, -1 );
28    drawing_mode( DRAW_MODE_SOLID, NULL, 0, 0 );
29  }
30 
31  // Multiply imagemap:
32  set_multiply_blender( 0, 0, 0, 255 );
33  draw_trans_sprite( m_pBmpTemp, m_pBmpTileMap[n], 0, 0 );
34  
35  // Draw mask: 
36  set_invert_blender( 0, 0, 0, 255 );
37  draw_trans_sprite( m_pBmpTemp, m_pBmpTileMask[n], 0, 0 );
38  
39  // Blit onto "video":
40  solid_mode();
41  masked_blit( m_pBmpTemp, bmp, 0, 0, v.x, v.y, m_iBlocksz, m_iBlocksz );
42}

Bob

Free Market Evangelist

September 2000

Quote:

I get the mask that I want, but it destroys everything else X|
Any ideas?

Try playing around with the last parameter of set_invert_blender(). 128 would be a good value to try.

--
- Bob
[ -- All my signature links are 404 -- ]

zyklus_

Member #8,481

April 2007

I've already tried that, and here's how it looked:

http://zyklus.acaro.org/host/puyo/debug06.jpg

What I don't understand is why, when I try to draw a masked bitmap with draw_sprite, the magenta changes into yellow

Is there any way I can tell a specific bitmap to ignore or change it's transparency color?

EDIT:

Ah, nvm; problem solved. It was a discreet problem and a slight programming error.
Apparently, when the mask was loaded into the bitmap, it ignored pixels with the mask color; I expected it to load the whole thing XD. Well, just a simple rectfill( ... makecol( 255, 0, 255 ); fixed the problem.