Rescale resampling weights so that the sum becomes one.

[movit] / resample_effect.cpp

diff --git a/resample_effect.cpp b/resample_effect.cpp
index 6c490f141bc1a87b9f86db44b90b5d64f75d0dd7..10dc59c5a2dbab0a0533629b801357636ad31ef0 100644 (file)
--- a/resample_effect.cpp
+++ b/resample_effect.cpp
@@ -299,11 +299,18 @@ void SingleResamplePassEffect::update_texture(GLuint glsl_program_num, const str
                int base_src_y = lrintf(center_src_y);
 
                // Now sample <int_radius> pixels on each side around that point.
+               double sum = 0.0;
                for (int i = 0; i < src_samples; ++i) {
                        int src_y = base_src_y + i - int_radius;
                        float weight = lanczos_weight(radius_scaling_factor * (src_y - center_src_y), LANCZOS_RADIUS);
                        weights[(y * src_samples + i) * 2 + 0] = weight * radius_scaling_factor;
                        weights[(y * src_samples + i) * 2 + 1] = (src_y + 0.5) / float(src_size);
+                       sum += weights[(y * src_samples + i) * 2 + 0];
+               }
+
+               // Normalize so that the sum becomes one.
+               for (int i = 0; i < src_samples; ++i) {
+                       weights[(y * src_samples + i) * 2 + 0] /= sum;
                }
        }