tiny.gpu.RenderDepthBias

1/// An offset added to each fragment's depth before the depth test, so that a decal drawn over a2/// coplanar surface passes a test the surface's own depth would tie. With `m` the triangle's3/// depth slope in pixels and `r` the step of depth32_float at the triangle's largest vertex depth4/// `z`, the offset is `o = m * slope + r * constant`, where `r = 2^(e - 23)` for `z = f * 2^e`5/// with `f` in [1, 2). A positive `clamp` caps `o` at `clamp`, a negative one floors `o` at6/// `clamp`, and zero leaves `o` unclamped. A bias that moves a depth outside [0, 1] leaves what7/// is stored to the backend: the CPU backend stores it as computed.8///9/// Vulkan lets `m` be `sqrt(dz/dx^2 + dz/dy^2)` or `max(|dz/dx|, |dz/dy|)`. The CPU backend takes10/// the maximum. The two agree when depth changes along one screen axis, and otherwise the maximum is11/// at most the root and at least 1/sqrt(2) of it, so a sloped bias matches another backend only12/// to that factor.13pub const RenderDepthBias = struct {14    constant: f32 = 0,15    slope: f32 = 0,16    clamp: f32 = 0,1718    pub fn valid(self: RenderDepthBias) bool {19        if (!std.math.isFinite(self.constant)) return false;20        if (!std.math.isFinite(self.slope)) return false;21        return std.math.isFinite(self.clamp);22    }2324    pub fn enabled(self: RenderDepthBias) bool {25        return self.constant != 0 or self.slope != 0;26    }27};

1pub const RenderDepthBias = contract.RenderDepthBias;