Method ray_for_pixel_jittered

tools/bloom-reference/src/main.rs:998–1009

Sub-pixel-jittered ray. `jitter` is in [0,1)² and samples different points within the pixel for multi-sample AA. Phase 1 always used (0.5, 0.5); Phase 2 lets the caller supply random offsets per sample.

(
        &self,
        pixel: UVec2,
        image_size: UVec2,
        jitter: Vec2,
    )

    /// always used (0.5, 0.5); Phase 2 lets the caller supply random
    /// offsets per sample.
    fn ray_for_pixel_jittered(
        &self,
        pixel: UVec2,
        image_size: UVec2,
        jitter: Vec2,
    ) -> Ray {
        let ndc_x = (2.0 * ((pixel.x as f32 + jitter.x) / image_size.x as f32) - 1.0) * self.aspect;
        let ndc_y = 1.0 - 2.0 * ((pixel.y as f32 + jitter.y) / image_size.y as f32);
        let scale = (self.fov_y_radians * 0.5).tan();
        let dir = self.forward + self.right * ndc_x * scale + self.up * ndc_y * scale;
        Ray::new(self.position, dir)
    }
}

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