4 files changed, 107 insertions, 13 deletions

diff --git a/common_features.mk b/common_features.mk
index fbfbc3ebc..8e9bcf0b9 100644
--- a/common_features.mk
+++ b/common_features.mk
@@ -178,6 +178,14 @@ ifeq ($(strip $(RGB_MATRIX_ENABLE)), WS2812)
     SRC += ws2812.c
 endif
 
+ifeq ($(strip $(RGB_MATRIX_CUSTOM_KB)), yes)
+    OPT_DEFS += -DRGB_MATRIX_CUSTOM_KB
+endif
+
+ifeq ($(strip $(RGB_MATRIX_CUSTOM_USER)), yes)
+    OPT_DEFS += -DRGB_MATRIX_CUSTOM_USER
+endif
+
 ifeq ($(strip $(TAP_DANCE_ENABLE)), yes)
     OPT_DEFS += -DTAP_DANCE_ENABLE
     SRC += $(QUANTUM_DIR)/process_keycode/process_tap_dance.c
diff --git a/docs/feature_rgb_matrix.md b/docs/feature_rgb_matrix.md
index f2168ab16..4ce9d15f0 100644
--- a/docs/feature_rgb_matrix.md
+++ b/docs/feature_rgb_matrix.md
@@ -177,7 +177,7 @@ enum rgb_matrix_effects {
     RGB_MATRIX_GRADIENT_UP_DOWN,    // Static gradient top to bottom, speed controls how much gradient changes
     RGB_MATRIX_BREATHING,           // Single hue brightness cycling animation
     RGB_MATRIX_CYCLE_ALL,           // Full keyboard solid hue cycling through full gradient
-    RGB_MATRIX_CYCLE_LEFT_RIGHT,    // Full gradient scrolling left to right 
+    RGB_MATRIX_CYCLE_LEFT_RIGHT,    // Full gradient scrolling left to right
     RGB_MATRIX_CYCLE_UP_DOWN,       // Full gradient scrolling top to bottom
     RGB_MATRIX_RAINBOW_MOVING_CHEVRON,  // Full gradent Chevron shapped scrolling left to right
     RGB_MATRIX_DUAL_BEACON,         // Full gradient spinning around center of keyboard
@@ -203,7 +203,7 @@ enum rgb_matrix_effects {
     RGB_MATRIX_EFFECT_MAX
 };
 ```
-    
+
 You can disable a single effect by defining `DISABLE_[EFFECT_NAME]` in your `config.h`:
 
 
@@ -236,17 +236,60 @@ You can disable a single effect by defining `DISABLE_[EFFECT_NAME]` in your `con
 |`#define DISABLE_RGB_MATRIX_SOLID_MULTISPLASH`         |Disables `RGB_MATRIX_SOLID_MULTISPLASH`        |
 
 
-## Custom layer effects
+## Custom RGB Matrix Effects
+
+By setting `RGB_MATRIX_CUSTOM_USER` (and/or `RGB_MATRIX_CUSTOM_KB`) in `rule.mk`, new effects can be defined directly from userspace, without having to edit any QMK core files.
+
+To declare new effects, create a new `rgb_matrix_user/kb.inc` that looks something like this:
 
-Custom layer effects can be done by defining this in your `<keyboard>.c`:
+`rgb_matrix_user.inc` should go in the root of the keymap directory.
+`rgb_matrix_kb.inc` should go in the root of the keyboard directory.
 
 ```C
-void rgb_matrix_indicators_kb(void) {
-    rgb_matrix_set_color(index, red, green, blue);
+// !!! DO NOT ADD #pragma once !!! //
+
+// Step 1.
+// Declare custom effects using the RGB_MATRIX_EFFECT macro
+// (note the lack of semicolon after the macro!)
+RGB_MATRIX_EFFECT(my_cool_effect)
+RGB_MATRIX_EFFECT(my_cool_effect2)
+
+// Step 2.
+// Define effects inside the `RGB_MATRIX_CUSTOM_EFFECT_IMPLS` ifdef block
+#ifdef RGB_MATRIX_CUSTOM_EFFECT_IMPLS
+
+// e.g: A simple effect, self-contained within a single method
+static bool my_cool_effect(effect_params_t* params) {
+  RGB_MATRIX_USE_LIMITS(led_min, led_max);
+  for (uint8_t i = led_min; i < led_max; i++) {
+    rgb_matrix_set_color(i, 0xff, 0xff, 0x00);
+  }
+  return led_max < DRIVER_LED_TOTAL;
+}
+
+// e.g: A more complex effect, relying on external methods and state, with
+// dedicated init and run methods
+static uint8_t some_global_state;
+static void my_cool_effect2_complex_init(effect_params_t* params) {
+  some_global_state = 1;
 }
+static bool my_cool_effect2_complex_run(effect_params_t* params) {
+  RGB_MATRIX_USE_LIMITS(led_min, led_max);
+  for (uint8_t i = led_min; i < led_max; i++) {
+    rgb_matrix_set_color(i, 0xff, some_global_state++, 0xff);
+  }
+
+  return led_max < DRIVER_LED_TOTAL;
+}
+static bool my_cool_effect2(effect_params_t* params) {
+  if (params->init) my_cool_effect2_complex_init(params);
+  return my_cool_effect2_complex_run(params);
+}
+
+#endif // RGB_MATRIX_CUSTOM_EFFECT_IMPLS
 ```
 
-A similar function works in the keymap as `rgb_matrix_indicators_user`.
+For inspiration and examples, check out the built-in effects under `quantum/rgb_matrix_animation/`
 
 
 ## Colors
diff --git a/quantum/rgb_matrix.c b/quantum/rgb_matrix.c
index 41ed8983e..5ca9b87a6 100644
--- a/quantum/rgb_matrix.c
+++ b/quantum/rgb_matrix.c
@@ -48,6 +48,19 @@
 #include "rgb_matrix_animations/solid_splash_anim.h"
 #include "rgb_matrix_animations/breathing_anim.h"
 
+#if defined(RGB_MATRIX_CUSTOM_KB) || defined(RGB_MATRIX_CUSTOM_USER)
+  #define RGB_MATRIX_CUSTOM_EFFECT_IMPLS
+    #define RGB_MATRIX_EFFECT(name, ...)
+    #ifdef RGB_MATRIX_CUSTOM_KB
+      #include "rgb_matrix_kb.inc"
+    #endif
+    #ifdef RGB_MATRIX_CUSTOM_USER
+      #include "rgb_matrix_user.inc"
+    #endif
+    #undef RGB_MATRIX_EFFECT
+  #undef RGB_MATRIX_CUSTOM_EFFECT_IMPLS
+#endif
+
 #ifndef RGB_DISABLE_AFTER_TIMEOUT
   #define RGB_DISABLE_AFTER_TIMEOUT 0
 #endif
@@ -81,6 +94,15 @@
   #define RGB_MATRIX_SPD_STEP 16
 #endif
 
+#if !defined(RGB_MATRIX_STARTUP_MODE)
+  #ifndef DISABLE_RGB_MATRIX_CYCLE_ALL
+    #define RGB_MATRIX_STARTUP_MODE RGB_MATRIX_CYCLE_LEFT_RIGHT
+  #else
+    // fallback to solid colors if RGB_MATRIX_CYCLE_LEFT_RIGHT is disabled in userspace
+    #define RGB_MATRIX_STARTUP_MODE RGB_MATRIX_SOLID_COLOR
+  #endif
+#endif
+
 bool g_suspend_state = false;
 
 rgb_config_t rgb_matrix_config;
@@ -104,12 +126,7 @@ void eeconfig_update_rgb_matrix(uint32_t val) {
 void eeconfig_update_rgb_matrix_default(void) {
   dprintf("eeconfig_update_rgb_matrix_default\n");
   rgb_matrix_config.enable = 1;
-#ifndef DISABLE_RGB_MATRIX_CYCLE_LEFT_RIGHT
-  rgb_matrix_config.mode = RGB_MATRIX_CYCLE_LEFT_RIGHT;
-#else
-  // fallback to solid colors if RGB_MATRIX_CYCLE_LEFT_RIGHT is disabled in userspace
-  rgb_matrix_config.mode = RGB_MATRIX_SOLID_COLOR;
-#endif
+  rgb_matrix_config.mode = RGB_MATRIX_STARTUP_MODE;
   rgb_matrix_config.hue = 0;
   rgb_matrix_config.sat = UINT8_MAX;
   rgb_matrix_config.val = RGB_MATRIX_MAXIMUM_BRIGHTNESS;
@@ -435,6 +452,20 @@ static void rgb_task_render(uint8_t effect) {
 #endif // DISABLE_RGB_MATRIX_SOLID_MULTISPLASH
 #endif // RGB_MATRIX_KEYREACTIVE_ENABLED
 
+#if defined(RGB_MATRIX_CUSTOM_KB) || defined(RGB_MATRIX_CUSTOM_USER)
+  #define RGB_MATRIX_EFFECT(name, ...) \
+    case RGB_MATRIX_CUSTOM_##name: \
+      rendering = name(&rgb_effect_params); \
+      break;
+  #ifdef RGB_MATRIX_CUSTOM_KB
+    #include "rgb_matrix_kb.inc"
+  #endif
+  #ifdef RGB_MATRIX_CUSTOM_USER
+    #include "rgb_matrix_user.inc"
+  #endif
+  #undef RGB_MATRIX_EFFECT
+#endif
+
     // Factory default magic value
     case UINT8_MAX: {
         rgb_matrix_test();
diff --git a/quantum/rgb_matrix.h b/quantum/rgb_matrix.h
index 5fdc854f0..775cbeac0 100644
--- a/quantum/rgb_matrix.h
+++ b/quantum/rgb_matrix.h
@@ -142,6 +142,18 @@ enum rgb_matrix_effects {
   RGB_MATRIX_SOLID_MULTISPLASH,
 #endif // DISABLE_RGB_MATRIX_SOLID_MULTISPLASH
 #endif // RGB_MATRIX_KEYREACTIVE_ENABLED
+
+#if defined(RGB_MATRIX_CUSTOM_KB) || defined(RGB_MATRIX_CUSTOM_USER)
+  #define RGB_MATRIX_EFFECT(name, ...) RGB_MATRIX_CUSTOM_##name,
+  #ifdef RGB_MATRIX_CUSTOM_KB
+    #include "rgb_matrix_kb.inc"
+  #endif
+  #ifdef RGB_MATRIX_CUSTOM_USER
+    #include "rgb_matrix_user.inc"
+  #endif
+  #undef RGB_MATRIX_EFFECT
+#endif
+
   RGB_MATRIX_EFFECT_MAX
 };