Stop using infinities in wgsl shaders (#1594)

* Stop using infinities in wgsl shaders
This fixes rendering issues on Windows browsers (likely due to a bug in ANGLE?). However this operation is undefined by spec anyways. Instead we're now using  float min/max instead. Wgsl float constants are now following wgsl spec to the letter.

* spelling

* Fix assertion & point-size conversion issues in size.rs

crates/re_renderer/shader/global_bindings.wgsl

@@ -19,7 +19,7 @@ struct FrameUniformBuffer {
     pixels_from_point: f32,
 
     /// (tan(fov_y / 2) * aspect_ratio, tan(fov_y /2)), i.e. half ratio of screen dimension to screen distance in x & y.
-    /// Both values are set to positive infinity for orthographic projection
+    /// Both values are set to f32max for orthographic projection
     tan_half_fov: Vec2,
 
     // Size used for all point radii given with Size::AUTO.

crates/re_renderer/shader/outlines/jumpflooding_init_shared.wgsl

@@ -11,13 +11,13 @@ fn compute_pixel_coords(center_coord: IVec2, unnormalized_edge_pos_a_and_b: Vec4
 
     var pixel_coord_a: Vec2;
     if num_edges_a_and_b.x == 0.0 {
-        pixel_coord_a = Vec2(inf());
+        pixel_coord_a = Vec2(f32max);
     } else {
         pixel_coord_a = Vec2(center_coord) + edge_pos_a_and_b.xy;
     }
     var pixel_coord_b: Vec2;
     if num_edges_a_and_b.y == 0.0 {
-        pixel_coord_b = Vec2(inf());
+        pixel_coord_b = Vec2(f32max);
     } else {
         pixel_coord_b = Vec2(center_coord) + edge_pos_a_and_b.zw;
     }

crates/re_renderer/shader/outlines/jumpflooding_step.wgsl

@@ -22,10 +22,10 @@ fn main(in: FragmentInput) -> @location(0) Vec4 {
     let pixel_step = Vec2(f32(uniforms.step_width), f32(uniforms.step_width)) / resolution;
     let pixel_coordinates = resolution * in.texcoord;
 
-    var closest_positions_a = Vec2(-inf());
-    var closest_distance_sq_a = inf();
-    var closest_positions_b = Vec2(-inf());
-    var closest_distance_sq_b = inf();
+    var closest_positions_a = Vec2(f32min);
+    var closest_distance_sq_a = f32max;
+    var closest_positions_b = Vec2(f32min);
+    var closest_distance_sq_b = f32max;
 
     for (var y: i32 = -1; y <= 1; y += 1) {
         for (var x: i32 = -1; x <= 1; x += 1) {

crates/re_renderer/shader/types.wgsl

@@ -12,12 +12,23 @@ type Mat3 = mat3x3<f32>;
 type Mat4x3 = mat4x3<f32>;
 type Mat4 = mat4x4<f32>;
 
-const f32min = -3.4028235e38;
-const f32max = 3.4028235e38;
-const f32eps = 0.00000011920928955078125;
-
+// Extreme values as documented by the spec:
+// https://www.w3.org/TR/WGSL/#floating-point-types
+const f32max = 0x1.fffffep+127f;  // Largest positive float value.
+const f32min = -0x0.fffffep+127f;  // Smallest negative float value.
+const f32min_normal = 0x1p-126f;  // Smallest positive normal float value.
+// F16 is not implemented yet in Naga https://github.com/gfx-rs/naga/issues/1884
+//const f16min = 0x0.ffcp+15h;  // Smallest negative float value.
+//const f16max = 0x1.ffcp+15h;  // Largest positive float value.
+//const f16min_normal = 0x1p-14h;   // Smallest positive normal float value.
+// https://www.w3.org/TR/WGSL/#integer-types
+const i32min = -0x80000000i;
+const i32max = 0x7fffffffi;
 const u32min = 0u;
-const u32max = 0xFFFFFFFFu;
+const u32max = 0xffffffffu;
+
+// Difference between `1.0` and the next larger representable number.
+const f32eps = 0.00000011920928955078125;
 
 const X = Vec3(1.0, 0.0, 0.0);
 const Y = Vec3(0.0, 1.0, 0.0);
@@ -26,6 +37,14 @@ const Z = Vec3(0.0, 0.0, 1.0);
 const ZERO = Vec4(0.0, 0.0, 0.0, 0.0);
 const ONE  = Vec4(1.0, 1.0, 1.0, 1.0);
 
-fn inf() -> f32 {
-    return 1.0 / 0.0;
-}
+
+// Do NOT use inf() or nan() in your WGSL shaders. Ever.
+// The WGSL spec allows implementations to assume that neither Inf or NaN are ever occurring:
+// https://www.w3.org/TR/WGSL/#floating-point-evaluation
+//
+// It will work most of the time, but there are rare cases where this will break.
+// (Notably, we had a case where the following commented inf function would silently break shaders when using ANGLE, i.e. in browsers on Windows!)
+//
+// fn inf() -> f32 {
+//     return 1.0 / 0.0;
+// }

crates/re_renderer/shader/utils/camera.wgsl

@@ -2,12 +2,12 @@
 
 // True if the camera is orthographic
 fn is_camera_orthographic() -> bool {
-    return frame.tan_half_fov.x == inf();
+    return frame.tan_half_fov.x >= f32max;
 }
 
 // True if the camera is perspective
 fn is_camera_perspective() -> bool {
-    return frame.tan_half_fov.x != inf();
+    return frame.tan_half_fov.x < f32max;
 }
 
 struct Ray {

crates/re_renderer/shader/utils/size.wgsl

@@ -6,11 +6,11 @@
 fn unresolved_size_to_world(_unresolved_size: f32, camera_distance: f32, auto_size: f32) -> f32 {
     // Resolve auto size.
     var unresolved_size: f32;
-    if _unresolved_size == inf() {
-        // positive inf for small auto size
+    if _unresolved_size >= f32max {
+        // positive max for small auto size
         unresolved_size = auto_size;
-    } else if _unresolved_size == -inf() {
-        // negative inf for large auto size
+    } else if _unresolved_size <= f32min {
+        // negative max for large auto size
         let large_factor = 1.33;
         unresolved_size = auto_size * large_factor;
     } else {

crates/re_renderer/src/global_bindings.rs

@@ -36,7 +36,7 @@ pub(crate) struct FrameUniformBuffer {
     pub pixels_from_point: f32,
 
     /// (tan(fov_y / 2) * aspect_ratio, tan(fov_y /2)), i.e. half ratio of screen dimension to screen distance in x & y.
-    /// Both values are set to positive infinity for orthographic projection
+    /// Both values are set to f32max for orthographic projection
     pub tan_half_fov: wgpu_buffer_types::Vec2,
 
     // Size used for all point radii given with Size::AUTO.

crates/re_renderer/src/renderer/lines.rs

@@ -424,13 +424,13 @@ impl LineDrawData {
             Vec::with_capacity(wgpu::util::align_to(num_segments, POSITION_TEXTURE_SIZE) as usize);
         // sentinel at the beginning to facilitate caps.
         position_data_staging.push(LineVertex {
-            position: glam::vec3(f32::INFINITY, f32::INFINITY, f32::INFINITY),
+            position: glam::vec3(f32::MAX, f32::MAX, f32::MAX),
             strip_index: u32::MAX,
         });
         position_data_staging.extend(vertices.iter());
         // placeholder at the end to facilitate caps.
         position_data_staging.push(LineVertex {
-            position: glam::vec3(f32::INFINITY, f32::INFINITY, f32::INFINITY),
+            position: glam::vec3(f32::MAX, f32::MAX, f32::MAX),
             strip_index: u32::MAX,
         });
         position_data_staging.extend(std::iter::repeat(gpu_data::LineVertex::zeroed()).take(

crates/re_renderer/src/size.rs

@@ -13,17 +13,17 @@ pub struct Size(pub f32);
 
 impl Size {
     /// Automatically sized, based on a view builder setting.
-    pub const AUTO: Self = Self(f32::INFINITY);
+    pub const AUTO: Self = Self(f32::MAX);
 
     /// Like [`Size::AUTO`], but larger by some small factor (~2).
-    pub const AUTO_LARGE: Self = Self(-f32::INFINITY);
+    pub const AUTO_LARGE: Self = Self(f32::MIN);
 
     /// Creates a new size in scene units.
     ///
     /// Values passed must be finite positive.
     #[inline]
     pub fn new_scene(size: f32) -> Self {
-        debug_assert!(size.is_finite() && size >= 0.0, "Bad size: {size}");
+        debug_assert!((0.0..f32::MAX).contains(&size), "Bad size: {size}");
         Self(size)
     }
 
@@ -32,27 +32,26 @@ impl Size {
     /// Values passed must be finite positive.
     #[inline]
     pub fn new_points(size: f32) -> Self {
-        debug_assert!(size.is_finite() && size >= 0.0, "Bad size: {size}");
+        debug_assert!((0.0..f32::MAX).contains(&size), "Bad size: {size}");
         Self(-size)
     }
 
     /// Returns true if the size is an automatically determined size ([`Self::AUTO`] or [`Self::AUTO_LARGE`]).
     #[inline]
     pub fn is_auto(&self) -> bool {
-        self.0.is_infinite()
+        self.0 <= f32::MIN || self.0 >= f32::MAX
     }
 
     /// Get the scene-size of this, if stored as a scene size.
     #[inline]
-    #[allow(unused)] // wgpu is not yet using this
     pub fn scene(&self) -> Option<f32> {
-        (self.0.is_finite() && self.0 >= 0.0).then_some(self.0)
+        (0.0..f32::MAX).contains(&self.0).then_some(self.0)
     }
 
     /// Get the point size of this, if stored as a point size.
     #[inline]
     pub fn points(&self) -> Option<f32> {
-        (self.0.is_finite() && self.0 <= 0.0).then_some(-self.0)
+        (self.0 > f32::MIN && self.0 <= 0.0).then_some(-self.0)
     }
 }
 
@@ -69,6 +68,7 @@ impl std::ops::Mul<f32> for Size {
     #[inline]
     fn mul(self, rhs: f32) -> Self::Output {
         debug_assert!(rhs.is_finite() && rhs >= 0.0);
+        debug_assert!((self.0 * rhs).is_finite());
         Self(self.0 * rhs)
     }
 }
@@ -77,6 +77,7 @@ impl std::ops::MulAssign<f32> for Size {
     #[inline]
     fn mul_assign(&mut self, rhs: f32) {
         debug_assert!(rhs.is_finite() && rhs >= 0.0);
+        debug_assert!((self.0 * rhs).is_finite());
         self.0 *= rhs;
     }
 }

crates/re_renderer/src/view_builder.rs

@@ -352,7 +352,7 @@ impl ViewBuilder {
                         }
                     };
 
-                    let tan_half_fov = glam::vec2(f32::INFINITY, f32::INFINITY);
+                    let tan_half_fov = glam::vec2(f32::MAX, f32::MAX);
                     let pixel_world_size_from_camera_distance =
                         vertical_world_size / config.resolution_in_pixel[1] as f32;