From 2736884f467eb2de2b2a9442b42f8d2dfbd60762 Mon Sep 17 00:00:00 2001
From: Tiago Batista Cardoso <tiago.cardoso7485@gmail.com>
Date: Tue, 24 Feb 2026 18:28:01 +0100
Subject: [PATCH] colorz

---
 .gitignore |  1 +
 render.c   | 44 +++++++++++++++-----------------------------
 2 files changed, 16 insertions(+), 29 deletions(-)
 create mode 100644 .gitignore

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..567609b
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+build/
diff --git a/render.c b/render.c
index f31c28a..1a87bbd 100644
--- a/render.c
+++ b/render.c
@@ -6,17 +6,20 @@
 
 #define WINDOW_WIDTH 800
 #define WINDOW_HEIGHT 600
-#define NODE_RADIUS 15
-#define ITERATIONS 500 // layout simulation steps
-#define COOLING 0.97 // temperature cooling rate
+#define NODE_RADIUS 5
+#define ITERATIONS 1000 // layout simulation steps
+#define COOLING 1 // temperature cooling rate
 
-typedef struct {
+struct layout_node_t {
 	double x, y; // position
 	double vx, vy; // velocity / displacement
-} layout_node_t;
+};
+typedef struct layout_node_t layout_node_t;
 
-static void draw_circle(SDL_Renderer *renderer, int cx, int cy, int r)
+// display a simple node of radius r
+static void draw_node(SDL_Renderer *renderer, int cx, int cy, int r)
 {
+	SDL_SetRenderDrawColor(renderer, 215, 153, 33, 255);
 	for (int dy = -r; dy <= r; dy++) {
 		int dx = (int)sqrt((double)(r * r - dy * dy));
 		SDL_RenderDrawLine(renderer, cx - dx, cy + dy, cx + dx,
@@ -24,7 +27,7 @@ static void draw_circle(SDL_Renderer *renderer, int cx, int cy, int r)
 	}
 }
 
-// Fruchterman-Reingold force-directed layout
+// compute a layout based on the fruchtermann-reingold algorithm.
 static layout_node_t *compute_layout(const graph_t *graph)
 {
 	int n = graph->n;
@@ -32,8 +35,6 @@ static layout_node_t *compute_layout(const graph_t *graph)
 	if (!nodes)
 		return NULL;
 
-	// Seed random positions
-	srand((unsigned)time(NULL));
 	for (int i = 0; i < n; i++) {
 		nodes[i].x = (double)(rand() % (WINDOW_WIDTH - 100)) + 50;
 		nodes[i].y = (double)(rand() % (WINDOW_HEIGHT - 100)) + 50;
@@ -42,15 +43,13 @@ static layout_node_t *compute_layout(const graph_t *graph)
 	}
 
 	double area = (WINDOW_WIDTH - 200) * (WINDOW_HEIGHT - 200);
-	double k = sqrt(area / n); // optimal distance between nodes
-	double temp = WINDOW_WIDTH * 0.1; // initial temperature
+	double k = sqrt(area / n);
+	double temp = WINDOW_WIDTH * 0.1;
 
 	for (int iter = 0; iter < ITERATIONS; iter++) {
-		// Reset displacements
 		for (int i = 0; i < n; i++)
 			nodes[i].vx = nodes[i].vy = 0.0;
 
-		// Repulsive forces (all pairs)
 		for (int i = 0; i < n; i++) {
 			for (int j = i + 1; j < n; j++) {
 				double dx = nodes[i].x - nodes[j].x;
@@ -70,7 +69,6 @@ static layout_node_t *compute_layout(const graph_t *graph)
 			}
 		}
 
-		// Attractive forces (edges only)
 		for (int i = 0; i < n; i++) {
 			node_t *neighbor = graph->adj_lists[i];
 			while (neighbor) {
@@ -95,7 +93,6 @@ static layout_node_t *compute_layout(const graph_t *graph)
 			}
 		}
 
-		// Apply displacements, clamped to temperature
 		for (int i = 0; i < n; i++) {
 			double disp = sqrt(nodes[i].vx * nodes[i].vx +
 					   nodes[i].vy * nodes[i].vy);
@@ -115,7 +112,6 @@ static layout_node_t *compute_layout(const graph_t *graph)
 					       nodes[i].y));
 		}
 
-		// Cool the temperature
 		temp *= COOLING;
 	}
 
@@ -134,11 +130,11 @@ void render_graph(SDL_Renderer *renderer, const graph_t *graph)
 		return;
 
 	// Clear background
-	SDL_SetRenderDrawColor(renderer, 200, 200, 200, 255);
+	SDL_SetRenderDrawColor(renderer, 48, 48, 48, 255);
 	SDL_RenderClear(renderer);
 
 	// Draw edges
-	SDL_SetRenderDrawColor(renderer, 30, 30, 30, 255);
+	SDL_SetRenderDrawColor(renderer, 189, 189, 189, 255);
 	for (int i = 0; i < n; i++) {
 		node_t *neighbor = graph->adj_lists[i];
 
@@ -160,17 +156,7 @@ void render_graph(SDL_Renderer *renderer, const graph_t *graph)
 		int y = (int)layout[i].y;
 
 		// Node fill
-		SDL_SetRenderDrawColor(renderer, 100, 149, 237, 255);
-		draw_circle(renderer, x, y, NODE_RADIUS);
-
-		// Node border
-		SDL_SetRenderDrawColor(renderer, 200, 220, 255, 255);
-		for (int deg = 0; deg < 360; deg++) {
-			double a = deg * M_PI / 180.0;
-			SDL_RenderDrawPoint(renderer,
-					    x + (int)(NODE_RADIUS * cos(a)),
-					    y + (int)(NODE_RADIUS * sin(a)));
-		}
+		draw_node(renderer, x, y, NODE_RADIUS);
 	}
 
 	free(layout);