# HP Prime for All

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TRIANGLE([G], x1, y1, x2, y2, x3, y3, c1, [c2, c3], [Alpha], ["ZString", z1, z2, z3]) or TRIANGLE([G], {x1, y1, [c1], [z1]}, {x2, y2, [c2], [z2]},{x3, y3, [c3], [z3]}, ["ZString"]) or TRIANGLE([G], [[x/y coordinate matrix]], [[color matrix]], {[[z matrix]], [zcode], [[[projection matrix]]], [zstring]) or TRIANGLE([G])

Draws a triangle between specified cartesian coordinates in the graphic using the specified color and transparency (0 ≤ Alpha ≤ 255). If 3 colors are specified, blends the colors in between the vertexes.
The next form of TRIANGLE allows display of multiple triangles at a time.
This is mostly used if you have a set of vertices and want to display them all at once.
The first 2 matrices indicate the x/y coordinates and colors of each points. TRIANGLE will draw 1 quadrilateral for each set of 4 adjacent vertices and blends the colors associated with the 4 points.
If a z and projection matrix are provided, for each point, this matrix is multiplied by the [x,y,z,1] vector to create the display x,y coordinates.
If zcode is a list that contains 3 real numbers { ex, ey, ez } then x,y are further modified by doing x=ez/z*x-ex and y=ez/z*y-ey creating a perspective projection.
If zstring is provided, z clipping will happen using the z value (see below).
If zcode="N" or is a list that starts with "N", then each z is normalized to be between 0 and 255.
About ZString
TRIANGLE([G]) returns a string adapted for z clipping.
To use Z clipping, call TRIANGLE to create a Z clipping string (initialized at 255 for each pixels). You can then call TRIANGLE with appropriate z (0-255) values for each of the triangle vertexes and TRIANGLE will not draw pixels further than the already drawn pixels. ZString is automatically updated as appropriate.

TRIANGLE(0,0,5,5,5,-5,#FFh,#FF00h,#FF0000h,128)