From 061884ced61cc5a29ead39f5aa8f843764b98782 Mon Sep 17 00:00:00 2001
From: Albeleon <37343812+Albeleon@users.noreply.github.com>
Date: Sun, 27 May 2018 15:48:54 +0200
Subject: [PATCH] RandomBlocks Transition

Changes to add functionality with RandomBlocks transition. The changes are:

- Utils.h: Function &GetRNG() added, which returns the common random number generator which will be needed for our function in graphics.cpp

- Utils.cpp: Function &Utils::GetRNG() added.

- Graphics.cpp:

  -> Library <array> added, to use the functions "begin" and "end".

  -> An anonymous namespace with two constant expressions: "random_size_blocks" (defines the width and height of each random block) and "random_array_size_blocks" (defines the number of blocks needed to cover the whole screen. This number (4800) was calculated after doing the operation (320 / random_size_blocks) * (240 / random_size_blocks) ).

  -> A variable "random_blocks" added in the namespace "Graphics", and initiated in "Graphics::Init". It's an array with the size of random_array_size_blocks (4800) and each value has a sequential number (0, 1, 2, ..., 4799) which we will use as an index for each block.

  -> In "Graphics::Transition" (each time the transition is invoked) we do a "Shuffle" to the array so the numbers are in a random order. We use here begin(), end() and Utils::GetRNG().

  -> In "Graphics::UpdateTransition", we create the function that inserts blocks. The "percentage" affects the number of blocks being invoked.
---
 src/graphics.cpp | 29 ++++++++++++++++++++++++++++-
 src/utils.cpp    |  4 ++++
 src/utils.h      |  8 ++++++++
 3 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/src/graphics.cpp b/src/graphics.cpp
index e41619445c..cead9aa3ae 100644
--- a/src/graphics.cpp
+++ b/src/graphics.cpp
@@ -19,6 +19,7 @@
 #include <algorithm>
 #include <sstream>
 #include <vector>
+#include <array>
 
 #include "graphics.h"
 #include "bitmap.h"
@@ -33,6 +34,11 @@
 #include "message_overlay.h"
 #include "scene.h"
 
+namespace {
+	constexpr uint32_t size_random_blocks = 4;
+	constexpr uint32_t size_array_random_blocks = 4800;
+}
+
 namespace Graphics {
 	void UpdateTitle();
 	void DrawFrame();
@@ -60,6 +66,8 @@ namespace Graphics {
 
 	std::unique_ptr<MessageOverlay> message_overlay;
 	std::unique_ptr<FpsOverlay> fps_overlay;
+
+	std::array<uint32_t, size_array_random_blocks> random_blocks;
 }
 
 unsigned SecondToFrame(float const second) {
@@ -80,6 +88,10 @@ void Graphics::Init() {
 	fps_overlay.reset(new FpsOverlay());
 
 	next_fps_time = 0;
+
+	for (uint32_t i = 0; i < size_array_random_blocks; i++) {
+		random_blocks[i] = i;
+	}
 }
 
 void Graphics::Quit() {
@@ -250,6 +262,10 @@ void Graphics::Transition(TransitionType type, int duration, bool erase) {
 			else
 				screen1 = screen2;
 		}
+
+		if (type == TransitionRandomBlocks) {
+			std::shuffle(random_blocks.begin(), random_blocks.end(), Utils::GetRNG());
+		}
 	}
 
 	screen_erased = erase;
@@ -274,7 +290,6 @@ void Graphics::UpdateTransition() {
 	// Fallback to FadeIn/Out for not implemented transition types:
 	// (Remove from here when implemented below)
 	switch (transition_type) {
-	case TransitionRandomBlocks:
 	case TransitionRandomBlocksUp:
 	case TransitionRandomBlocksDown:
 	case TransitionZoomIn:
@@ -296,6 +311,18 @@ void Graphics::UpdateTransition() {
 		dst->Blit(0, 0, *screen2, screen2->GetRect(), 255 * percentage / 100);
 		break;
 	case TransitionRandomBlocks:
+		dst->Blit(0, 0, *screen1, screen1->GetRect(), 255);
+		for (uint32_t i = 0; i < size_array_random_blocks * percentage / 100; i++) {
+			dst->Blit(random_blocks[i] % (w / size_random_blocks) * size_random_blocks,
+				random_blocks[i] / (w / size_random_blocks) * size_random_blocks,
+				*screen2,
+				Rect(
+					random_blocks[i] % (w / size_random_blocks) * size_random_blocks,
+					random_blocks[i] / (w / size_random_blocks) * size_random_blocks,
+					size_random_blocks,
+					size_random_blocks),
+				255);
+		}
 		break;
 	case TransitionRandomBlocksUp:
 		break;
diff --git a/src/utils.cpp b/src/utils.cpp
index d156e9094d..445607338a 100644
--- a/src/utils.cpp
+++ b/src/utils.cpp
@@ -383,6 +383,10 @@ int32_t Utils::GetRandomNumber(int32_t from, int32_t to) {
 	return int32_t(ures);
 }
 
+std::mt19937 &Utils::GetRNG() {
+	return rng;
+}
+
 bool Utils::ChanceOf(int32_t n, int32_t m) {
 	assert(n >= 0 && m > 0);
 	return GetRandomNumber(1, m) <= n;
diff --git a/src/utils.h b/src/utils.h
index 48bb78c99e..4e7bc2bf3c 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -22,6 +22,7 @@
 #include <string>
 #include <sstream>
 #include <vector>
+#include <random>
 #include "system.h"
 
 namespace Utils {
@@ -172,6 +173,13 @@ namespace Utils {
 	 */
 	int32_t GetRandomNumber(int32_t from, int32_t to);
 
+	/**
+	 * Gets the seeded Random Number Generator (RNG).
+	 *
+	 * @return the random number generator
+	 */
+	std::mt19937 &GetRNG();
+
 	/**
 	 * Has an n/m chance of returning true. If n>m, always returns true.
 	 *