matrix: Increase global rounding precision

Author: johannes-wolf

CHANGES.md

@@ -25,6 +25,8 @@
 - Fixed a bug when passing a coordinate to the `angle:` argument of
   `content` and a transformation matrix ≠ id.
 - Fixed a bug with cetz creating invalid stroke objects for `stroke: none` (#1059).
+- Increased the rounding digits from 8 to 10, fixing some rounding bugs
+  with `ortho`.
 
 # 0.4.2
 - The `tree` element now has a `anchor:` argument to position the tree (#929)

src/draw/projection.typ

@@ -162,33 +162,40 @@
 // - sorted (bool): Sort drawables by maximum distance (front to back)
 // - cull-face (none,str): Enable back-face culling if set to `"cw"` for clockwise
 //   or `"ccw"` for counter-clockwise. Polygons of the specified order will not get drawn.
-#let _projection(body, view-matrix, projection-matrix, reset-transform: true, sorted: true, cull-face: "cw") = {
+// - flatten (bool): Set $z=0$ for all geometry
+#let _projection(body, view-matrix, projection-matrix, reset-transform: true, sorted: true, cull-face: "cw", flatten: false) = {
   (ctx => {
     let transform = ctx.transform
     let perspective-mode = type(projection-matrix) == function
     let previous-perspective-mode = ctx.at("_perspective-projection", default: false)
     if perspective-mode {
       ctx._perspective-projection = true
     }
-    ctx.transform = view-matrix
 
-    let (ctx, drawables, bounds) = process.many(ctx, util.resolve-body(ctx, body))
+    let local-ctx = ctx
+    let local-transform = if flatten {
+      local-ctx.transform = matrix.mul-mat(
+        ((1,0,0,0), (0,1,0,0), (0,0,0,0), (0,0,0,1.0)),
+        view-matrix)
+    } else {
+      local-ctx.transform = view-matrix
+    }
+
+    let (ctx, drawables, bounds) = process.many(local-ctx, util.resolve-body(ctx, body))
 
     if cull-face != none {
       assert(cull-face in ("cw", "ccw"),
         message: "cull-face must be none, cw or ccw.")
       drawables = _filter-cw-faces(drawables, mode: cull-face)
     }
+
     if sorted {
       drawables = _sort-by-distance(drawables)
     }
 
-    if projection-matrix != none {
-      drawables = drawable.apply-transform(projection-matrix, drawables)
-    }
-
     ctx.transform = transform
     if perspective-mode {
+      drawable.apply-transform(projection-matrix, drawables)
       ctx._perspective-projection = previous-perspective-mode
     }
     if not reset-transform {

src/matrix.typ

@@ -3,7 +3,7 @@
 #let cetz-core = plugin("../cetz-core/cetz_core.wasm")
 
 // Global rounding precision
-#let precision = 8
+#let precision = 10
 
 #let _round = calc.round.with(digits: precision)
 
@@ -243,7 +243,7 @@
 /// - ..matrices (matrix): The matrices to multiply from left to right.
 /// -> matrix
 #let mul-mat(..matrices) = {
-  matrices = matrices.pos()
+  matrices = matrices.pos().filter(m => m != none)
   let out = matrices.first()
   for i in range(1, matrices.len()) {
     let matrix = matrices.at(i)