1 files changed, 74 insertions, 0 deletions

diff --git a/quantum/rgb_matrix_animations/digital_rain_anim.h b/quantum/rgb_matrix_animations/digital_rain_anim.h
new file mode 100644
index 000000000..4ba3c1c87
--- /dev/null
+++ b/quantum/rgb_matrix_animations/digital_rain_anim.h
@@ -0,0 +1,74 @@
+#pragma once
+#ifndef DISABLE_RGB_MATRIX_DIGITAL_RAIN
+
+#ifndef RGB_DIGITAL_RAIN_DROPS
+    // lower the number for denser effect/wider keyboard
+    #define RGB_DIGITAL_RAIN_DROPS 24
+#endif
+
+bool rgb_matrix_digital_rain(effect_params_t* params) {
+  // algorithm ported from https://github.com/tremby/Kaleidoscope-LEDEffect-DigitalRain
+  const uint8_t drop_ticks           = 28;
+  const uint8_t pure_green_intensity = 0xd0;
+  const uint8_t max_brightness_boost = 0xc0;
+  const uint8_t max_intensity        = 0xff;
+
+  static uint8_t map[MATRIX_COLS][MATRIX_ROWS] = {{0}};
+  static uint8_t drop = 0;
+
+  if (params->init) {
+    rgb_matrix_set_color_all(0, 0, 0);
+    memset(map, 0, sizeof map);
+    drop = 0;
+  }
+  for (uint8_t col = 0; col < MATRIX_COLS; col++) {
+    for (uint8_t row = 0; row < MATRIX_ROWS; row++) {
+      if (row == 0 && drop == 0 && rand() < RAND_MAX / RGB_DIGITAL_RAIN_DROPS) {
+        // top row, pixels have just fallen and we're
+        // making a new rain drop in this column
+        map[col][row] = max_intensity;
+      }
+      else if (map[col][row] > 0 && map[col][row] < max_intensity) {
+        // neither fully bright nor dark, decay it
+        map[col][row]--;
+      }
+      // set the pixel colour
+      uint8_t led[LED_HITS_TO_REMEMBER];
+      uint8_t led_count = rgb_matrix_map_row_column_to_led(row, col, led);
+
+      // TODO: multiple leds are supported mapped to the same row/column
+      if (led_count > 0) {
+        if (map[col][row] > pure_green_intensity) {
+          const uint8_t boost = (uint8_t) ((uint16_t) max_brightness_boost * (map[col][row] - pure_green_intensity) / (max_intensity - pure_green_intensity));
+          rgb_matrix_set_color(led[0], boost, max_intensity, boost);
+        }
+        else {
+          const uint8_t green = (uint8_t) ((uint16_t) max_intensity * map[col][row] / pure_green_intensity);
+          rgb_matrix_set_color(led[0], 0, green, 0);
+        }
+      }
+    }
+  }
+  if (++drop > drop_ticks) {
+    // reset drop timer
+    drop = 0;
+    for (uint8_t row = MATRIX_ROWS - 1; row > 0; row--) {
+      for (uint8_t col = 0; col < MATRIX_COLS; col++) {
+        // if ths is on the bottom row and bright allow decay
+        if (row == MATRIX_ROWS - 1 && map[col][row] == max_intensity) {
+          map[col][row]--;
+        }
+        // check if the pixel above is bright
+        if (map[col][row - 1] == max_intensity) {
+          // allow old bright pixel to decay
+          map[col][row - 1]--;
+          // make this pixel bright
+          map[col][row] = max_intensity;
+        }
+      }
+    }
+  }
+  return false;
+}
+
+#endif // DISABLE_RGB_MATRIX_DIGITAL_RAIN