From d7def3f9e42e72566d7aedd52ffdeb5851da8314 Mon Sep 17 00:00:00 2001 From: "Steinar H. Gunderson" Date: Mon, 15 Jan 2018 20:45:59 +0100 Subject: [PATCH 1/1] Microoptimization in calculate_scaling_weights. Doesn't actually influence the benchmarks much, but is useful to get 100% equivalence with the coming compute shader. --- resample_effect.cpp | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/resample_effect.cpp b/resample_effect.cpp index 690f15a..b6da2e2 100644 --- a/resample_effect.cpp +++ b/resample_effect.cpp @@ -605,15 +605,16 @@ ScalingWeights calculate_scaling_weights(unsigned src_size, unsigned dst_size, f // to compute the destination pixel, and how many depend on the scaling factor. // Thus, the kernel width will vary with how much we scale. float radius_scaling_factor = min(scaling_factor, 1.0f); - int int_radius = lrintf(LANCZOS_RADIUS / radius_scaling_factor); - int src_samples = int_radius * 2 + 1; + const int int_radius = lrintf(LANCZOS_RADIUS / radius_scaling_factor); + const int src_samples = int_radius * 2 + 1; unique_ptr[]> weights(new Tap[dst_samples * src_samples]); float subpixel_offset = offset - lrintf(offset); // The part not covered by whole_pixel_offset. assert(subpixel_offset >= -0.5f && subpixel_offset <= 0.5f); + float inv_scaling_factor = 1.0f / scaling_factor; for (unsigned y = 0; y < dst_samples; ++y) { // Find the point around which we want to sample the source image, // compensating for differing pixel centers as the scale changes. - float center_src_y = (y + 0.5f) / scaling_factor - 0.5f; + float center_src_y = (y + 0.5f) * inv_scaling_factor - 0.5f; int base_src_y = lrintf(center_src_y); // Now sample pixels on each side around that point. -- 2.39.2