From b5e820f7c361842aca1b53332f9e27b67eff18d4 Mon Sep 17 00:00:00 2001
From: davidovski <david@sendula.com>
Date: Fri, 23 Apr 2021 09:26:10 +0100
Subject: [PATCH] initial commit

---
 Makefile        | 12 +++++++++
 brotshader.c    | 70 +++++++++++++++++++++++++++++++++++++++++++++++++
 mandelbrot.glsl | 45 +++++++++++++++++++++++++++++++
 3 files changed, 127 insertions(+)
 create mode 100644 Makefile
 create mode 100644 brotshader.c
 create mode 100644 mandelbrot.glsl

diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..c956781
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,12 @@
+PROG=brotshader
+CC=gcc
+FLAGS=-lm `pkg-config -libs raylib`
+
+.DEFAULT_GOAL := run
+
+${PROG}: ${PROG}.c
+	${CC} ${PROG}.c -o ${PROG} ${FLAGS}
+
+run: ${PROG}
+	./${PROG} 
+
diff --git a/brotshader.c b/brotshader.c
new file mode 100644
index 0000000..d0fd96b
--- /dev/null
+++ b/brotshader.c
@@ -0,0 +1,70 @@
+#include <raylib.h>
+
+const int width = 1280;
+const int height = 1280;
+
+int main() {
+	InitWindow(width, height, "brotshader");
+	
+	Shader shader = LoadShader(0, "mandelbrot.glsl");
+	
+	RenderTexture2D target = LoadRenderTexture(width, height);
+
+	float c[2] = {0, 0};
+
+	float offset[2] = {0, 0};
+	float zoom = 2.0f;
+	int max = 255;
+
+	int resolutionLoc    = GetShaderLocation(shader, "resolution");
+	int locationLoc      = GetShaderLocation(shader, "location");
+	int zoomLoc          = GetShaderLocation(shader, "zoom");
+	int maxLoc           = GetShaderLocation(shader, "max");
+	
+	float screen[2] = {(float)width, (float)height};
+
+	SetShaderValue(shader, resolutionLoc, screen, UNIFORM_VEC2);
+	SetShaderValue(shader, locationLoc, &offset, UNIFORM_VEC2);
+	SetShaderValue(shader, zoomLoc, &zoom, UNIFORM_FLOAT);
+	SetShaderValue(shader, maxLoc, &max, UNIFORM_INT);
+
+	SetTargetFPS(60);
+
+	while (!WindowShouldClose()) {
+	
+		if (IsKeyDown(KEY_UP)) offset[1] -= zoom * 0.01f;
+		if (IsKeyDown(KEY_DOWN)) offset[1] += zoom * 0.01f;
+		if (IsKeyDown(KEY_RIGHT)) offset[0] -= zoom * 0.01f;
+		if (IsKeyDown(KEY_LEFT)) offset[0] += zoom * 0.01f;
+
+		if (IsKeyDown(KEY_W)) zoom -= zoom * 0.01f;
+		if (IsKeyDown(KEY_S)) zoom += zoom * 0.01f;
+		if (IsKeyDown(KEY_A)) max -= 1;
+		if (IsKeyDown(KEY_D)) max += 1;
+
+		SetShaderValue(shader, resolutionLoc, screen, UNIFORM_VEC2);
+		SetShaderValue(shader, locationLoc, &offset, UNIFORM_VEC2);
+		SetShaderValue(shader, zoomLoc, &zoom, UNIFORM_FLOAT);
+		SetShaderValue(shader, maxLoc, &max, UNIFORM_INT);
+
+		BeginDrawing();
+
+		ClearBackground(RAYWHITE);
+
+		BeginTextureMode(target);
+		DrawRectangle(0, 0, width, height, BLACK);
+		EndTextureMode();
+
+		BeginShaderMode(shader);
+		DrawTexture(target.texture, 0, 0, WHITE);
+		EndShaderMode();
+		
+		EndDrawing();
+	}
+
+	UnloadShader(shader);
+	UnloadRenderTexture(target);
+
+	CloseWindow();
+}
+
diff --git a/mandelbrot.glsl b/mandelbrot.glsl
new file mode 100644
index 0000000..d3d0ee2
--- /dev/null
+++ b/mandelbrot.glsl
@@ -0,0 +1,45 @@
+#version 100
+precision highp float;
+
+uniform vec2 resolution;
+uniform vec2 location;
+uniform double zoom;
+
+uniform int max;
+
+vec2 compsquare(vec2 z) {
+    float temp = z.x;
+    z.x = z.x * z.x - z.y * z.y;
+    z.y = 2.0 * temp * z.y;
+    return z;
+}
+
+vec3 hsv2rgb(vec3 hue){
+    vec4 K = vec4(1.0, 2.0/3.0, 1.0/3.0, 3.0);
+    vec3 p = abs(fract(hue.xxx + K.xyz) * 6.0 - K.www);
+    return hue.z * mix(K.xxx, clamp(p - K.xxx, 0.0, 1.0), hue.y);
+}
+
+vec3 mandelbort(vec2 point){
+    vec2 z = vec2(0.0);
+    float iters = 0.0;
+    for (iters = 0.0;   iters < float(max); ++iters)
+    {
+        z = compsquare(z) + point;
+        if(dot(z, z) > 4.0) break;
+    }
+    float hue = iters / float(max);
+    if(hue > 0.98) return vec3(0.0);
+    return hsv2rgb(vec3(hue, 1.0, 1.0));
+}
+
+void main()
+{
+    vec2 uv = gl_FragCoord.xy / resolution;
+    uv.x *= resolution.x / resolution.y;
+    uv -= vec2(0.7, 0.5);
+    uv *= zoom;
+    uv -= location;
+
+    gl_FragColor = vec4(mandelbort(uv), 1.0);
+}