FreeBSD Manual Pages
image_tesselation(3) Arcan Lua API image_tesselation(3) NAME image_tesselation - alter the tesselation level of a vid SYNOPSIS nil image_tesselation( vid:id ) image_tesselation( vid:id, func:callback ) image_tesselation( vid:id, float:s, float:t ) image_tesselation( vid:id, float:s, float:t, bool:depth ) image_tesselation( vid:id, float:s, float:t, func:callback ) image_tesselation( vid:id, float:s, float:t, bool:depth, func:callback ) DESCRIPTION This function is used to convert a normal vid to a pseudo-3D object in the sense that it becomes a tesselated plane with *s* steps in one dimension, and *t* steps in the other. This is intended for very specific effects, either by itself or when com- bined with a vertex shader stage. It is also usable for when you need to show a sparsely populated area efficiently as a point-cloud but without the setup of a 3D pipeline and a rendertarget. By setting *s* or *t* to 1, tesselation is disabled and the underlying mesh shape is deallocated. Updating the mesh shape to *s* > 1 and *t* > 1 will regenerate and repopulate the individual attributes for vertices and tex- ture coordinates. By setting the boolean depth argument after the *s* and *t* forms to false, image drawing will not require a depth buffer, avoiding the costly switch between 2D and 3D style processing. The vertices will be distributed in the -1..1 range (-1,-1 in upper left corner, 1,1 in lower right) while the texture coordinates go in the 0..1 range with 0,0 at the upper left corner. The storage can be accessed through the optional callback and has the sig- nature of (refobj, n_vertices, vertex_size) where refobj is a userdata ta- ble that supports: :vertices(ind) => x, y, z, w :vertices(ind, x, y, z, w) => nil for fetching and updating, with xyzw matching vertex_size (=2, only xy, =3 only xyz, => w,y,z). :colors(ind) => r, g, b, a :colors(ind, new_r, new_g, new_b, new_a) for fetching, activating and updating vertex colors. :texcos(ind, set_ind) => s, t :texcos(ind, set_ind, new_s, new_t) aliased as :texture_coordinates for fetching and updating texture coordinates, set_ind should be 0 or 1 as there are two possible set of texture coordi- nates per vertex. :primitive_type(0 or 1) for switching between triangle soup (0) and point- cloud (1) when rendering. If any of these storage blocks doesn't exist, an attempt to set an index will force it to be allocated. The plane is indexed, and the individual indices can be manipulated in or- der to create degenerate triangles that will be discarded. This is useful to 'slice out' parts of the plane. These can be accessed via: :in- dices(ind) => p1x, p1y, p2x, p2y, p2z, p3x, p3y, p3z :indices(ind, p1x, p1y, p2x, p2y, p2z, p3x, p3y, p3z) For a vertex size of 3. If the vertex size of 2, omitt the z arguments. NOTES 1 Picking operations like image_hit does not take tesselation into ac- count. This may be subject to change. 2 EXAMPLE function image_tesselation0() local tess = fill_surface(64, 64, 0, 255, 0); show_image(tess); image_tesselation(tess, 32, 32, function(obj, n_v, size) obj:primitive_type(1); end ); end SEE ALSO: image August 2026 image_tesselation(3)
NAME | SYNOPSIS | DESCRIPTION | NOTES | EXAMPLE | SEE ALSO:
Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=image_tesselation&sektion=3&manpath=FreeBSD+Ports+15.1.quarterly>