feat: add support for color and buffer shading

include/screen.hpp

@@ -1,34 +1,61 @@
 #pragma once
 
+#include "vec.hpp"
 #include <cstddef>
 #include <cstdlib>
 #include <cstdio>
 
+#include <functional>
 #include <unistd.h>
 #include <termios.h>
+#include <vector>
 
 struct Screen {
-    char *buf;
+    /**
+     * Unit pixel information struct
+     */
+    struct Symbol {
+	char sym;
+	vec<3> color = {0,0,0};
+	bool visible = true;
+
+	Symbol &operator=(char c) { sym = c; return *this; };
+    };
+
+    /**
+     * Function taking screen coords and space coords and returning a Symbol for
+     * that position
+     */
+    using char_shader_t = std::function<Symbol(int, int, float, float)>;
+
     std::size_t w, h;
 
     float dx = 0, dy = 0;
-    float sx = 1, sy = 1;
+    float sx = 1, sy = 1.8;
 
     void draw();
     void clear();
 
-    char &at(std::size_t n);
-    char &at(std::size_t x, std::size_t y);
+    Symbol &at(std::size_t n);
+    Symbol &at(int x, int y);
+    Symbol &at(float x, float y);
 
     void resize(std::size_t n);
     void resize(std::size_t x, std::size_t y);
 
+    std::pair<float, float> screen_to_xy(int w, int h);
+    std::pair<int, int> xy_to_screen(float x, float y);
+
     Screen(std::size_t n) : buf(nullptr) { resize(n); }
     Screen(std::size_t x, std::size_t y) : buf(nullptr) { resize(x, y); }
     ~Screen() { delete[] buf; }
 
+    std::vector<const vec<2>*> points;
+    char_shader_t shader;
+
 private:
-    char _dummy;
+    Symbol *buf;
+    Symbol _dummy;
 
     static inline void gotoxy(int x, int y)
     {
@@ -36,6 +63,19 @@ private:
     }
 };
 
+using colorizer_t = std::function<vec<3>(float)>;
+
+struct TanhColorizer {
+    float scale = 1.0;
+    float translate = 0.0;
+    vec<3> operator()(float y);
+
+private:
+    static vec<3> hsl_to_rgb(float h, float s, float l);
+    static float hue_to_rgb(float p, float q, float t);
+};
+
+
 static termios old, current;
 static inline void enter_noncanonical_mode(void)
 {