Refine the bresenham implementation

animation/animation.c

@@ -1,43 +1,82 @@
 #include "animation.h"
+#include <stdio.h>
 
-line_t line_new(uint8_t x0, uint8_t y0, uint8_t x1, uint8_t y1) {
-    uint8_t dx = x1 - x0;
-    int8_t dy = y1 - y0;
-    int8_t inc = dy > 0 ? 1 : dy == 0 ? 0 : -1;
-    int8_t m = 2 * dy;
-    int8_t error = 0;
+time_line_t time_line_new(int t0, int y0, int t1, int y1) {
+    int dt = t1 - t0;
+    int dy = y1 - y0;
+    int de = 2 * dy;
 
-    if (m > 0) {
-        error = m - dx;
+    int inc = dy > 0 ? 1 : dy == 0 ? 0 : -1;
+    int error;
+    
+    if (de > 0) {
+        error = de - dt;
     } else {
-        error = m + dx;
+        error = de + dt;
     }
 
-    return (line_t){ .y = y0, .m = m, .error = error, .inc = inc, .dx = dx };
+    return (time_line_t){ .y = y0, .dt = dt, .de = de, .error = error, .inc = inc, .dy = dy };
 }
 
-uint8_t line_next(line_t *slope) {
+int time_line_next(time_line_t *self) {
+    int error = self->error + self->de;
+
+    if (self->de > 0) {
+        while (error >= 0) {
+            self->y += self->inc;
+            error -= 2 * self->dt;
+        }
+    } else {
+        while (error < 0) {
+            self->y -= self->inc;
+            error += 2 * self->dt;
+        }
+    }
+
+    self->error = error;
+    return self->y;
+}
+
+/*
+time_line_t time_line_new(int t0, int y0, int t1, int y1) {
+    int dt = t1 - t0;
+    int dy = y1 - y0;
+    int inc = dy > 0 ? 1 : dy == 0 ? 0 : -1;
+    int m = 2 * dy;
+    int error = 0;
+
+    if (m > 0) {
+        error = m - dt;
+    } else {
+        error = m + dt;
+    }
+
+    return (time_line_t){ .y = y0, .m = m, .error = error, .inc = inc, .dt = dt };
+}
+*/
+
+/*
+int time_line_next(time_line_t *slope) {
     slope->error += slope->m;
 
     if (slope->m > 0) {
         if (slope->error >= 0) {
             slope->y += slope->inc;
-            slope->error -= 2 * slope->dx;
+            slope->error -= 2 * slope->dt;
         }
     } else {
         if (slope->error <= 0) {
             slope->y += slope->inc;
-            slope->error += 2 * slope->dx;
+            slope->error += 2 * slope->dt;
         }
     }
 
     return slope->y;
 }
-
-/*
-void line_print(line_t *line) {
-    printf("y: %d\tm: %d\terror: %d\tinc: %d\t:dx: %d\n", line->y, line->m, line->error, line->inc, line->dx);
-}
 */
 
+void time_line_print(time_line_t *self) {
+    printf("y: %d\tde: %d\terror: %d\tinc: %d\t:dt: %d\n", self->y, self->de, self->error, self->inc, self->dt);
+}
+
 

animation/animation.h

@@ -1,25 +1,24 @@
 #ifndef __ANIMATION_H__
 #define __ANIMATION_H__
 
-#include <avr/io.h>
-
 // line_t provides a simplified implementation of Bresenham's line drawing
 // technique. At this time, it assumes a transition of x = 0 -> 60, and a dy
 // between -59 and 59. I am not sure I understand Bresenham's algorithm yet,
 // but I'll need to revisit all of this if I want to expand the boundaries.
-typedef struct line_s {
-    uint8_t y;
-    int8_t m;
-    int8_t error;
-    int8_t inc;
-    uint8_t dx;
-} line_t;
+typedef struct {
+    int y;
+    int de;
+    int error;
+    int inc;
+    int dt;
+    int dy;
+} time_line_t;
 
 // Construct a new line object. x1 must be greater than x0, and dy must be less than dx.
-line_t line_new(uint8_t x0, uint8_t y0, uint8_t x1, uint8_t y1);
+time_line_t time_line_new(int, int, int, int);
 
 // Calculate the next y value of the line.
-uint8_t line_next(line_t *line);
+int time_line_next(time_line_t *);
 
 // Diagnostic printout of the current state of line_t.
 // void line_print(line_t *line);

animation/bresenham.c

@@ -1,30 +1,30 @@
 #include <stdlib.h>
 
-void bresenham(int x1, int y1, int x2, int y2) {
-    int dx = x2 - x1;
+void bresenham_time(int t1, int y1, int t2, int y2) {
+    int dt = t2 - t1;
     int dy = y2 - y1;
     int m = 2 * dy;
     int err = 0;
 
     if (m > 0) {
-        err = m - dx;
+        err = m - dt;
     } else if (m < 0) {
-        err = m + dx;
+        err = m + dt;
     }
-    for (int x = x1, y = y1; x <= x2; x++) {
-        printf("(%d, %d) [%d]\n", x, y, err);
+    for (int t = t1, y = y1; t <= t2; t++) {
+        printf("(%d, %d) [%d]\n", t, y, err);
 
         err += m;
 
         if (m > 0) {
             if (err >= 0) {
                 y++;
-                err -= 2 * dx;
+                err -= 2 * dt;
             }
         } else if (m < 0) {
             if (err <= 0) {
                 y--;
-                err += 2 * dx;
+                err += 2 * dt;
             }
         }
     }

animation/main.c

@@ -1,21 +1,36 @@
 #include <stdlib.h>
-#include <base.h>
-#include <rng.h>
-
-typedef struct RGB_s {
-    uint8_t brightness;
-    uint8_t r;
-    uint8_t g;
-    uint8_t b;
-} rgb_t;
-
+#include <stdio.h>
+#include <animation.h>
 
 int main (void) {
-    rng_t rng = rng_new(0);
-    animation_t animation = animation_new();
+    {
+        time_line_t line = time_line_new(0, 0, 15, 10);
+        time_line_print(&line);
+        for (int i = 0; i < 15; i++) {
+            time_line_next(&line);
+            time_line_print(&line);
+        }
+    }
 
-    for (int i = 0; i < 120; i++) {
-        animation_step(&animation, &rng);
-        printf("[%d] %d %d %d\n", animation.frame, animation.lamp.r, animation.lamp.g, animation.lamp.b);
+    printf("\n");
+
+    {
+        time_line_t line = time_line_new(0, 0, 15, 25);
+        time_line_print(&line);
+        for (int i = 0; i < 15; i++) {
+            time_line_next(&line);
+            time_line_print(&line);
+        }
+    }
+
+    printf("\n");
+
+    {
+        time_line_t line = time_line_new(0, 0, 10, 255);
+        time_line_print(&line);
+        for (int i = 0; i < 10; i++) {
+            time_line_next(&line);
+            time_line_print(&line);
+        }
     }
 }

flake.nix

@@ -75,18 +75,18 @@
         };
 
       packages."x86_64-linux"."animation" =
-        { mcu, chip_select, f_cpu }:
+        # { gcc, mcu, chip_select, f_cpu }:
+        { gcc }:
         let
           pkgs = import nixpkgs { system = "x86_64-linux"; };
-          avr = pkgs.pkgsCross.avr.buildPackages;
         in pkgs.stdenv.mkDerivation rec {
           name = "animation";
           src = ./.;
 
-          CFLAGS = cflags { inherit mcu chip_select f_cpu; };
+          # CFLAGS = cflags { inherit mcu chip_select f_cpu; };
 
           buildPhase = ''
-            ${avr.gcc}/bin/avr-gcc ${CFLAGS} -o animation.o -c ${src}/animation/animation.c
+            ${gcc} -o animation.o -c ${src}/animation/animation.c
             '';
 
           installPhase = ''
@@ -95,6 +95,32 @@
             '';
         };
 
+      packages."x86_64-linux"."animation-test" =
+        let
+          pkgs = import nixpkgs { system = "x86_64-linux"; };
+          lib = pkgs.lib;
+        in pkgs.stdenv.mkDerivation rec {
+          name = "animation-test";
+          src = ./.;
+
+          buildInputs = [
+            (packages."x86_64-linux"."animation" { inherit gcc; })
+          ];
+
+          INCLUDE_DIRS = lib.concatStringsSep " " (map (dir: "-I${dir}") buildInputs);
+          OBJECT_FILES = lib.concatStringsSep " " (map (dir: "${dir}/*.o") buildInputs);
+          gcc = "${pkgs.gcc}/bin/gcc";
+
+          buildPhase = ''
+            ${gcc} ${INCLUDE_DIRS} -o main.o -c ${src}/animation/main.c
+            ${gcc} ${INCLUDE_DIRS} -o animation-test main.o ${OBJECT_FILES}
+            '';
+          installPhase = ''
+            mkdir $out
+            cp animation-test $out
+            '';
+        };
+
       packages."x86_64-linux"."sk9822" =
         { mcu, chip_select, f_cpu }:
         let