simpler stitching code

Uriopass · Dec 11, 2023 · 3ae46d7 · 3ae46d7
1 parent 04e86bb
commit 3ae46d7
Show file tree

Hide file tree

Showing 2 changed files with 14 additions and 24 deletions.
diff --git a/assets/shaders/terrain.vert.wgsl b/assets/shaders/terrain.vert.wgsl
@@ -15,7 +15,7 @@ struct VertexOutput {
 
 struct ChunkData {
     lod: u32,                 // 0 = most details, 1 = half details, 2 = quarter details, etc.
-    lod_pow2: f32,            // 2^lod
+    lod_pow2: u32,            // 2^lod
     resolution: u32,          // number of vertices per side
     distance_lod_cutoff: f32, // max distance at which to switch to the next lod to have smooth transitions
     cell_size: f32,           // size of a cell in world space at lod0
@@ -58,39 +58,29 @@ fn vert(@builtin(vertex_index) vid: u32,
     let idx_x: u32 = vid % cdata.resolution;
     let idx_y: u32 = vid / cdata.resolution;
 
-    var in_position: vec2<f32> = vec2(f32(idx_x), f32(idx_y)) * cdata.cell_size * cdata.lod_pow2;
+    var in_position: vec2<i32> = vec2(i32(idx_x), i32(idx_y));
 
-    let stitch_x_pos: bool = (stitch_dir_flags & 1u) != 0u;
-    let stitch_y_pos: bool = (stitch_dir_flags & 2u) != 0u;
-    let stitch_x_neg: bool = (stitch_dir_flags & 4u) != 0u;
-    let stitch_y_neg: bool = (stitch_dir_flags & 8u) != 0u;
-
-    if (stitch_x_pos && idx_x == cdata.resolution - 1u && (idx_y % 2u) == 1u) {
-        in_position = in_position - vec2<f32>(0.0, cdata.cell_size * cdata.lod_pow2);
+    if (idx_x == 0u) { // x_neg
+        in_position.y &= -1 << ((stitch_dir_flags & 4u) >> 2u);
     }
-    if (stitch_x_neg && idx_x == 0u && (idx_y % 2u) == 1u) {
-        in_position = in_position - vec2<f32>(0.0, cdata.cell_size * cdata.lod_pow2);
+    else if (idx_x == cdata.resolution - 1u) { // x_pos
+        in_position.y &= -1 << (stitch_dir_flags & 1u);
     }
-    if (stitch_y_pos && (vid >= (cdata.resolution * (cdata.resolution - 1u))) && ((idx_x) % 2u) == 1u) {
-        in_position = in_position - vec2<f32>(cdata.cell_size * cdata.lod_pow2, 0.0);
+    if (idx_y == 0u) { // y_neg
+        in_position.x &= -1 << ((stitch_dir_flags & 8u) >> 3u);
     }
-    if (stitch_y_neg && (vid < cdata.resolution) && ((idx_x) % 2u) == 1u) {
-        in_position = in_position - vec2<f32>(cdata.cell_size * cdata.lod_pow2, 0.0);
+    else if (idx_y == cdata.resolution - 1u) { // y_pos
+        in_position.x &= -1 << ((stitch_dir_flags & 2u) >> 1u);
     }
 
-    let tpos: vec2<i32> =  vec2<i32>((in_position + in_off) * cdata.inv_cell_size);
+    let tpos: vec2<i32> = in_position * i32(cdata.lod_pow2) + vec2<i32>(in_off * cdata.inv_cell_size);
 
     let texLoad: vec2<u32> = textureLoad(t_terraindata, tpos, 0).rg;
 
     let height: f32 = unpack_height(texLoad.r);
     let diffs: vec2<f32> = unpack_diffs(texLoad.g);
 
-    let step: i32 = i32(pow(2.0, f32(cdata.lod)));
-
-    let zf_off: vec2<i32> =  vec2( step * (i32(idx_x) % 2),
-                                   step * (i32(idx_y) % 2));
-
-    let world_pos: vec3<f32> = vec3(in_position + in_off, height);
+    let world_pos: vec3<f32> = vec3(vec2<f32>(in_position * i32(cdata.lod_pow2)) * cdata.cell_size + in_off, height);
 
     //let dist_to_cam: f32 = length(params.cam_pos.xyz - vec3(pos.xy, 0.0));
     //let transition_alpha: f32 = smoothstep(cdata.distance_lod_cutoff * 0.8, cdata.distance_lod_cutoff, dist_to_cam);

diff --git a/engine/src/drawables/terrain.rs b/engine/src/drawables/terrain.rs
@@ -62,7 +62,7 @@ impl<const CSIZE: usize, const CRESOLUTION: usize> TerrainRender<CSIZE, CRESOLUT
             let uni = Uniform::new(
                 TerrainChunkData {
                     lod: lod as u32,
-                    lod_pow2: scale as f32,
+                    lod_pow2: scale,
                     resolution: 1 + CRESOLUTION as u32 / scale,
                     distance_lod_cutoff: 2.0f32.powf(1.0 + LOD_MIN_DIST_LOG2 + lod as f32)
                         - std::f32::consts::SQRT_2 * CSIZE as f32,
@@ -338,7 +338,7 @@ u8slice_impl!(TerrainInstance);
 #[repr(C)]
 pub struct TerrainChunkData {
     lod: u32,                 // 0 = highest resolution, 1 = half resolution, etc.*
-    lod_pow2: f32,            // 2^lod
+    lod_pow2: u32,            // 2^lod
     resolution: u32,          // width of the vertex grid
     distance_lod_cutoff: f32, // max distance at which to switch to the next lod to have smooth transitions
     cell_size: f32,