Have expect_equal() pinpoint the pixel with the largest error when that test fails.

diff --git a/test_util.cpp b/test_util.cpp
index aa9cf5651aced8ef9f29e99c2ba3a093d565d3d2..047eb11a18a360de615f08249d50a034df64a5fe 100644 (file)
--- a/test_util.cpp
+++ b/test_util.cpp
@@ -72,16 +72,22 @@ void expect_equal(const float *ref, const float *result, unsigned width, unsigne
 {
        float largest_difference = -1.0f;
        float squared_difference = 0.0f;
+       int largest_diff_x = -1, largest_diff_y = -1;
 
        for (unsigned y = 0; y < height; ++y) {
                for (unsigned x = 0; x < width; ++x) {
                        float diff = ref[y * width + x] - result[y * width + x];
-                       largest_difference = std::max(largest_difference, fabsf(diff));
+                       if (fabs(diff) > largest_difference) {
+                               largest_difference = fabs(diff);
+                               largest_diff_x = x;
+                               largest_diff_y = y;
+                       }
                        squared_difference += diff * diff;
                }
        }
 
-       EXPECT_LT(largest_difference, largest_difference_limit);
+       EXPECT_LT(largest_difference, largest_difference_limit)
+               << "Largest difference is in x=" << largest_diff_x << ", y=" << largest_diff_y;
 
        float rms = sqrt(squared_difference) / (width * height);
        EXPECT_LT(rms, rms_limit);