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)
 {

src/screen.cpp

@@ -2,33 +2,113 @@
 #include <cstring>
 #include <screen.hpp>
 
+/* Screen */
+
 void Screen::resize(std::size_t n) {
     w = n; h = 1;
-    buf = (char *)realloc(buf, n * sizeof(char));
+    buf = (Symbol *)realloc(buf, n * sizeof(Symbol));
 }
 
 void Screen::resize(std::size_t x, std::size_t y) {
     w = x; h = y;
-    buf = (char *)realloc(buf, x * y * sizeof(char));
+    buf = (Symbol *)realloc(buf, x * y * sizeof(Symbol));
 }
 
-char &Screen::at(std::size_t n) { return buf[n]; }
-char &Screen::at(std::size_t x, std::size_t y) {
-    auto idx = (int)(((y-dy)/sy) * w) + (int)((x-dx)/sx);
-    if(idx >= w *h) return _dummy;
+Screen::Symbol &Screen::at(std::size_t n) { return buf[n]; }
+Screen::Symbol &Screen::at(int x, int y) {
+    auto idx = y * w + x;
+    if(idx < 0 || idx >= w * h) return _dummy;
     return buf[idx];
 }
 
+Screen::Symbol &Screen::at(float x, float y) {
+    auto [a, b] = xy_to_screen(x, y);
+    if(a < 0 || a >= w || b < 0 || b >= h) return _dummy;
+    return at(a, b);
+}
+
+std::pair<float, float> Screen::screen_to_xy(int x, int y) {
+    return {
+	x * sx + dx,
+	y * sy + dy
+    };
+}
+
+std::pair<int, int> Screen::xy_to_screen(float x, float y) {
+    return {
+	(x - dx)/sx,
+	(y - dy)/sy
+    };
+}
+
+
 void Screen::clear() {
-    memset(buf, ' ', w*h);
+    static const Symbol s {' ', {0,0,0}};
+    for(int i = 0; i < w * h; ++i)
+	memcpy(buf + i, &s, sizeof(Symbol));
 }
 
 void Screen::draw() {
+    // "shade" each pixel on screen with #this->shader()
+    for(int i = 0; i < h; ++i) {
+	for(int j = 0; j < w; ++j) {
+	    auto [x, y] = screen_to_xy(j, i);
+	    at(j, i) = shader(j, i, x, y);
+	}
+    }
+
+    // write out a '#' wherever we have a point registered
+    for(const auto &p : points) {
+	at(p->x, p->y) = {.sym = '#', .color = 1};
+    }
+
+    // print out each symbol in our buffer to the terminal
     gotoxy(0, 0);
     for(int i = 0; i < h; ++i) {
 	for(int j = 0; j < w; ++j) {
-	    std::fputc(at(j, i), stdout);
+	    const auto &sym = at(j, i);
+	    const auto color = sym.color.clamp({0,0,0}, {1,1,1}) * 255;
+	    printf("\033[48;2;%d;%d;%dm%c",
+		   (int)color.x, (int)color.y, (int)color.z, sym.sym);
 	}
-	std::fputc('\n', stdout);
+
+	// reset color, go to the next line
+	printf("\033[38;2;%d;%d;%dm\n", 0,0,0);
+    }
+
+}
+
+/* TanhColorizer */
+
+vec<3> TanhColorizer::operator()(float y) {
+    y = (std::tanh((y - translate)/scale * 2.25) + 1)/2.f;
+    float hue = (1.f - y) * 240.f / 360.f;
+    return hsl_to_rgb(hue, 1, 0.5);
+}
+
+vec<3> TanhColorizer::hsl_to_rgb(float h, float s, float l) {
+    float q = l < 0.5 ? l * (1 + s) : l + s - l * s;
+    float p = 2 * l - q;
+    float r = hue_to_rgb(p, q, h + 0.33);
+    float g = hue_to_rgb(p, q, h);
+    float b = hue_to_rgb(p, q, h - 0.33);
+    return { r, g, b };
+}
+
+float TanhColorizer::hue_to_rgb(float p, float q, float t) {
+    if (t < 0) {
+	t += 1;
+    } else if (t > 1) {
+	t -= 1;
+    }
+
+    if (t >= 0.66) {
+	return p;
+    } else if (t >= 0.5) {
+	return p + (q - p) * (0.66 - t) * 6;
+    } else if (t >= 0.33) {
+	return q;
+    } else {
+	return p + (q - p) * 6 * t;
     }
 }