Fix error in TesselatedSvgNode::join - offset indices correctly

Author: fschutt

azul-core/src/gl.rs

@@ -672,8 +672,9 @@ uniform vec2 vBboxSize;
 attribute vec2 vAttrXY;
 
 void main() {
-    gl_Position = vec4(vAttrXY / vBboxSize - vec2(1.0), 1.0, 1.0);
-    gl_PointSize = 1.0;
+    vec2 vCalc = vAttrXY / vBboxSize;
+    vec2 vCalc1 = vCalc - vec2(1.0, 1.0);
+    gl_Position = vec4(vCalc1, 0.0, 1.0);
 }";
 
 static SVG_FRAGMENT_SHADER: &[u8] = b"#version 150

azulc/src/svg.rs

@@ -454,6 +454,21 @@ pub fn join_tessellated_nodes(nodes: &[TessellatedSvgNode]) -> TessellatedSvgNod
 
     use rayon::iter::IntoParallelRefIterator;
     use rayon::iter::ParallelIterator;
+    use rayon::iter::IndexedParallelIterator;
+    use rayon::iter::IntoParallelRefMutIterator;
+
+    let mut index_offset = 0;
+
+    // note: can not be parallelized!
+    let all_index_offsets = nodes
+    .as_ref()
+    .iter()
+    .map(|t| {
+        let i = index_offset;
+        index_offset += t.vertices.len();
+        i
+    })
+    .collect::<Vec<_>>();
 
     let all_vertices = nodes
     .as_ref()
@@ -464,9 +479,27 @@ pub fn join_tessellated_nodes(nodes: &[TessellatedSvgNode]) -> TessellatedSvgNod
     let all_indices = nodes
     .as_ref()
     .par_iter()
-    .flat_map(|t| {
+    .enumerate()
+    .flat_map(|(buffer_index, t)| {
+
+        // since the vertex buffers are now joined,
+        // offset the indices by the vertex buffers lengths
+        // encountered so far
+        let vertex_buffer_offset: u32 = all_index_offsets
+            .get(buffer_index)
+            .copied()
+            .unwrap_or(0)
+            .min(core::u32::MAX as usize) as u32;
+
         let mut indices = t.indices.clone().into_library_owned_vec();
+        if vertex_buffer_offset != 0 {
+            indices
+            .par_iter_mut()
+            .for_each(|i| { *i += vertex_buffer_offset; });
+        }
+
         indices.push(GL_RESTART_INDEX);
+
         indices
     })
     .collect::<Vec<_>>();

examples/rust/opengl.rs

@@ -163,12 +163,17 @@ fn parse_multipolygons(data: &str) -> Vec<SvgMultiPolygon> {
 
                         let mut current = SvgPoint { x: i[0], y: i[1] };
                         current.x -= 13.804493;
-                        current.x *= 10000.0;
                         current.y -= 51.05264;
-                        current.y *= 10000.0;
+                        current.x *= 50000.0;
+                        current.y *= 50000.0;
+                        current.x += 500.0;
+                        current.y += 500.0;
+                        current.x *= 2.0;
+                        current.y *= 2.0;
 
                         last = Some(current);
                         let last_point = last_point?;
+
                         Some(SvgPathElement::Line(SvgLine { start: last_point, end: current }))
                     }).collect::<Vec<_>>().into(),
                 }