From b7443d800bddcdc7f3e5feaa0130df2445af4160 Mon Sep 17 00:00:00 2001 From: truelight Date: Wed, 13 Jun 2007 16:21:11 +0000 Subject: (svn r10143) -Add: store the filename of the grfs opened and allow easy access to the name -Codechange: store the SpriteID in the spritecache too -Add: add a PNG loader for graphical files -Documentation: added a document to explain the PNG format --- docs/32bpp.txt | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) create mode 100644 docs/32bpp.txt (limited to 'docs/32bpp.txt') diff --git a/docs/32bpp.txt b/docs/32bpp.txt new file mode 100644 index 000000000..b847dd522 --- /dev/null +++ b/docs/32bpp.txt @@ -0,0 +1,36 @@ +32bpp and OpenTTD +================= + +OpenTTD has 32bpp support. This means: OpenTTD still is 8bpp, but it has the +posibility to override the graphics with 32bpp. This means that it isn't a +replacement of grf or newgrf, but simply an addition. If you want to use 32bpp +graphics of a newgrf, you do need the newgrf itself too (with 8bpp graphics). + + +The Format +---------- + +32bpp images are stored in PNG. They should go in: + data/sprites//.png + +For example, a grfname would be 'openttd' (without .grf, lowercase), and the +SpriteID 3, to override the 3rd sprite in openttd.grf with a 32bpp version. + +The format of this PNG can be almost anything, but we advise to use RGBA +format. Alpha-channel is fully supported. + +As the core of OpenTTD is 8bpp, and because you of course want company colours +in your images, you will need to add a mask for every sprite that needs colour +remapping. The name is simular as above, only you have to put a 'm' behind the +SpriteID. This image should be a 8bpp palette image, where the palette is the +OpenTTD palette. Upon load of the PNG, the mask is loaded too, and overrides +the RGB (not the Alpha) of the original PNG image, and replacing it with a +8bpp color remapped and converted to 32bpp. + +An other thing that OpenTTD needs in your png, is 2 tEXt chunks: x_offs and +y_offs. This to define the x- and y-offset, of course. Use the tool we supply +to add this information. Sadly enough most graphical editors trashes those +chunks upon save, so you have to readd it every time you save your image. + +Your images should be the same as the grf, in size. + -- cgit v1.2.3-54-g00ecf