Use list in rasteriser

compile

@@ -14,6 +14,7 @@ RAYTRACER_SRC="src/window/*.c \
 RASTERISER_SRC="src/window/*.c \
 	src/vector/*.c \
 	src/scene/*.c \
+	src/list/*.c \
 	src/rasteriser/*.c \
 	src/math/*.c \
 "

include/rasteriser/rasteriser.h

@@ -1,9 +1,13 @@
 #ifndef RASTERISER_H
 #define RASTERISER_H
 
+#include "c_cpp_aliases/aliases.h"
+#include "list/typed_list.h"
 #include "vector/vec.h"
 #include "window/window.h"
 
+MAKE_LIST_TYPE(f32);
+
 typedef struct {
   vec2i_t p0;
   vec2i_t p1;

src/rasteriser/rasteriser.c

@@ -1,23 +1,76 @@
 #include "rasteriser/rasteriser.h"
 #include "c_cpp_aliases/aliases.h"
+#include "list/typed_list.h"
 #include "vector/vec.h"
 #include "window/window.h"
+#include <assert.h>
+#include <stdio.h>
+#include <sys/mman.h>
+
+internal list_float_t *interpolate(i32 i0, f32 d0, i32 i1, f32 d1);
 
 void draw_line(window_t *wnd, line_t line, colour_t colour) {
-  if (line.p1.x < line.p0.x) {
-    vec_swap(vec2i_t, line.p0, line.p1);
-  }
-
   i32 x0 = line.p0.x;
   i32 y0 = line.p0.y;
   i32 x1 = line.p1.x;
   i32 y1 = line.p1.y;
 
-  f32 a = ((f32)y1 - y0) / ((f32)x1 - x0);
+  list_float_t *values = NULL;
-  f32 y = y0;
+
+  if (abs(x1 - x0) > abs(y1 - y0)) {
+    if (line.p1.x < line.p0.x) {
+      vec_swap(vec2i_t, line.p0, line.p1);
+    }
+
+    values = interpolate(x0, y0, x1, y1);
+    if (!values) {
+      return;
+    }
 
     for (i32 x = x0; x <= x1; ++x) {
-    set_pixel(wnd, x, (i32)y, colour);
+      set_pixel(wnd, x, (i32)(get(values, x - x0)), colour);
-    y += a;
     }
+  } else {
+    if (line.p1.y < line.p0.y) {
+      vec_swap(vec2i_t, line.p0, line.p1);
+    }
+
+    values = interpolate(y0, x0, y1, x1);
+    if (!values) {
+      return;
+    }
+
+    for (i32 y = y0; y <= y1; ++y) {
+      set_pixel(wnd, (i32)(get(values, y - y0)), y, colour);
+    }
+  }
+
+  destroy_list(f32, values);
+}
+
+internal list_float_t *interpolate(i32 i0, f32 d0, i32 i1, f32 d1) {
+  list_float_t *values;
+  if (i0 == i1) {
+    values = create_list_with_capacity(f32, 20);
+    if (values) {
+      append(f32, values, d0);
+    }
+
+    return values;
+  }
+
+  values = create_list(f32);
+  if (!values) {
+    return NULL;
+  }
+
+  f32 a = (d1 - d0) / ((f32)i1 - i0);
+  f32 d = d0;
+
+  for (i32 i = i0; i <= i1; ++i) {
+    append(f32, values, d);
+    d += a;
+  }
+
+  return values;
 }