ttri - nesbox/TIC-80 GitHub Wiki

ttri(x1, y1, x2, y2, x3, y3, u1, v1, u2, v2, u3, v3, [texsrc=0], [chromakey=-1], [z1=0], [z2=0], [z3=0])

Parameters

• x1, y1 : The screen coordinates of the first vertex.
• x2, y2 : The screen coordinates of the second vertex.
• x3, y3 : The screen coordinates of the third vertex.
• u1, v1 : The UV coordinates for the first vertex.
• u2, v2 : The UV coordinates for the second vertex.
• u3, v3 : The UV coordinates for the third vertex.
• texsrc : If set to 0 (default), the triangle's texture is read from TILES RAM. If set to 1, the texture comes from the MAP RAM. If set to 2, the texture comes from the screen RAM in the VBANK for which the function isn't being called – that is, a ttri() triangle that's drawn to vbank(0)'s screen with the texsrc value set to 2 will use vbank(1)'s screen as its texture and vice versa.
• chromakey : The palette index (or array of palette indices 0.80) that will be used as transparent.
• z1, z2, z3 : Depth parameters for perspective correction and depth buffer

A note on UV Coordinates

The letters "U" and "V" denote the axes of the 2D texture because "X", "Y" are already used. These can be thought of as the window inside TILES or MAP RAM. Note that the sprite sheet or map in this case is treated as a single large image, with U and V addressing its pixels directly, rather than by sprite ID. So for example the top left corner of sprite #2 would be located at u=16 (horizontal), v=0 (vertical).

Description

This function draws a triangle filled with texture from TILES RAM, MAP RAM, or the screen buffer of the VBANK for which the function isn't being called.

Depth Buffer

A depth buffer is implemented in ttri when z1, z2, z3 arguments are set. The depth buffer can be cleared using the cls() function.

Examples

-- title:  triangle demo
-- author: MonstersGoBoom
-- desc:   wiki demo for ttri
-- script: lua
-- input:  gamepad

usize = 32
vsize = 32
function TIC()
  cls(1)
  if btn(0) then usize=usize-1 end
  if btn(1) then usize=usize+1 end
  if btn(2) then vsize=vsize-1 end
  if btn(3) then vsize=vsize+1 end

-- draw a scaling view into the map ram

  ttri(0,0,
         64,0,
         0,64,
         0,0,
         usize,0,
         0,vsize,
         true,
         14)
  ttri(64,0,
         0,64,
         64,64,
         usize,0,
         0,vsize,
         usize,vsize,
         true,
         14)
end

UV show

• Sprite x,y,z rotation with ttri here