init

4 files changed, 195 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..e0edfe1
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+*.ff
+*.png
+pineapple
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..78828dc
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,16 @@
+.POSIX:
+.SUFFIXES:
+
+CFLAGS = -O2 -Wall -Wextra -pedantic
+LDFLAGS = -static
+LDLIBS = -lm
+
+all: pineapple
+
+pineapple: pineapple.c
+	$(CC) $(CFLAGS) $(LDFLAGS) $< -o $@ $(LDLIBS)
+
+clean:
+	rm -f pineapple
+
+.PHONY: all clean
diff --git a/pineapple.c b/pineapple.c
new file mode 100644
index 0000000..8911622
--- /dev/null
+++ b/pineapple.c
@@ -0,0 +1,176 @@
+#include <endian.h>
+#include <fcntl.h>
+#include <getopt.h>
+#include <math.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#define PI 3.14159265358979323846
+
+#define die(code, msg) do { fprintf(stderr, "pineapple: %s\n", msg); exit(code); } while (0);
+
+#define USAGE "pineapple [-v] [-f | -a]"
+#define dieusage() die(100, "usage: " USAGE)
+
+#define ASCII_CHARS "$@B%8&WM#*oahkbdpqwmZO0QLCJUYXzcvunxrjft/\\|()1{}[]?-_+~<>i!lI;:,\"^`'. "
+
+typedef struct { float x, y, z; } vec3;
+
+struct __attribute__((__packed__)) triangle {
+	vec3 normal;
+	vec3 vertices[3];
+	uint16_t _attr_count; /* unused */
+};
+
+static inline vec3
+vadd(vec3 a, vec3 b)
+{
+	return (vec3){ a.x + b.x, a.y + b.y, a.z + b.z };
+}
+
+static inline vec3
+vsub(vec3 a, vec3 b)
+{
+	return (vec3){ a.x - b.x, a.y - b.y, a.z - b.z };
+}
+
+static inline vec3
+smul(vec3 v, float s)
+{
+	return (vec3){ v.x * s, v.y * s, v.z * s };
+}
+
+static inline float
+dot(vec3 a, vec3 b)
+{
+	return a.x * b.x + a.y * b.y + a.z * b.z;
+}
+
+static inline vec3
+cross(vec3 a, vec3 b)
+{
+	return (vec3){ a.y*b.z - b.y*a.z, a.z*b.x - b.z*a.x, a.x*b.y - b.x*a.y };
+}
+
+static inline float
+magnitude(vec3 v)
+{
+	return sqrt(dot(v, v));
+}
+
+static inline vec3
+vnorm(vec3 v)
+{
+	float mag = magnitude(v);
+	return (vec3){ v.x / mag, v.y / mag, v.z / mag };
+}
+
+float
+ray_triangle_intersect(vec3 P, vec3 d, struct triangle tri)
+{
+	vec3 n = tri.normal, A = tri.vertices[0], B = tri.vertices[1], C = tri.vertices[2];
+	d = vnorm(d);
+	n = vnorm(n);
+	if (dot(n, d) == 0.0) return NAN;
+	float t = (dot(n, A) - dot(n, P)) / dot(n, d);
+	vec3 Q = vadd(P, smul(d, t));
+	if (dot(cross(vsub(B, A), vsub(Q, A)), n) >= 0.0 &&
+		dot(cross(vsub(C, B), vsub(Q, B)), n) >= 0.0 &&
+		dot(cross(vsub(A, C), vsub(Q, C)), n) >= 0.0)
+		return t;
+	return NAN;
+}
+
+int
+main(int argc, char *argv[])
+{
+	int c;
+	int verbosity = 0;
+	enum { ASCII, FARBFELD } mode = ASCII;
+	while ((c = getopt(argc, argv, "vfa")) > 0) {
+		switch (c) {
+			case 'v': verbosity++; break;
+			case 'f': mode = FARBFELD; break;
+			case 'a': mode = ASCII; break;
+			default: dieusage();
+		}
+	}
+	argv += optind; argc -= optind;
+	if (argc > 0) dieusage();
+	
+	const char *stl;
+	{
+		int stl_fd = open("pineapple.stl", O_RDONLY);
+		if (stl_fd < 0) die(111, "fatal: unable to open pineapple.stl");
+		struct stat stl_stat;
+		if (fstat(stl_fd, &stl_stat) < 0) die(111, "fatal: unable to stat pineapple.stl");
+		stl = mmap(NULL, stl_stat.st_size, PROT_READ, MAP_PRIVATE, stl_fd, 0);
+		close(stl_fd);
+		if (!stl) die(111, "fatal: unable to mmap pineapple.stl");
+	}
+	stl += 80;
+	uint32_t len = le32toh(*(uint32_t *)stl);
+	stl += sizeof(uint32_t);
+	const struct triangle *triangles = (const struct triangle *)stl;
+
+	vec3 camera_pos = { -70.0, 60.0, 60.0 };
+	float camera_phi = PI * 0.8;
+	float camera_theta = PI * 0.5;
+	float fov = 80.0 * PI / 180.0;
+	vec3 light = { 0.0, 0.0, -1.0 };
+
+	uint32_t width = 106;
+	uint32_t height = 53;
+
+	if (mode == FARBFELD) {
+		uint32_t wbe = htobe32(width);
+		uint32_t hbe = htobe32(height);
+		fwrite("farbfeld", 1, 8, stdout);
+		fwrite(&wbe, 1, 4, stdout);
+		fwrite(&hbe, 1, 4, stdout);
+	}
+
+	for (int h = height - 1; h >= 0; --h) {
+		if (verbosity >= 1) fprintf(stderr, "row %d/%d\r", height - h - 1, height);
+		for (uint32_t w = 0; w < width; ++w) {
+			float theta = camera_theta - fov/2.0 + fov/height*h;
+			float phi = camera_phi - fov/2.0 + fov/width*w;
+			vec3 dir = { sinf(theta) * cosf(phi), sinf(theta) * sinf(phi), cosf(theta) };
+			dir = vnorm(dir);
+
+			float shortest = INFINITY;
+			vec3 shortest_norm = {0};
+			for (size_t i = 0; i < len; ++i) {
+				float d = ray_triangle_intersect(camera_pos, dir, triangles[i]);
+				if (d != NAN && fabs(d) < fabs(shortest)) {
+					shortest = d;
+					shortest_norm = triangles[i].normal;
+				}
+			}
+
+			float brightness = 0.0;
+			if (shortest != INFINITY) {
+				float light_angle = acosf(dot(shortest_norm, light) / magnitude(shortest_norm) / magnitude(light));
+				brightness = 1 - light_angle / PI;
+			}
+			if (mode == ASCII) {
+				printf("%c", ASCII_CHARS[strlen(ASCII_CHARS) - 1 - (int)(brightness * strlen(ASCII_CHARS))]);
+			} else if (mode == FARBFELD) {
+				uint16_t x = htobe16((uint16_t)(brightness * 0xffff));
+				uint16_t a = htobe16(0xffff);
+				fwrite(&x, 1, 2, stdout);
+				fwrite(&x, 1, 2, stdout);
+				fwrite(&x, 1, 2, stdout);
+				fwrite(&a, 1, 2, stdout);
+			}
+		}
+		if (mode == ASCII) printf("\n");
+	}
+
+	return 0;
+}
\ No newline at end of file
diff --git a/pineapple.stl b/pineapple.stl
new file mode 100644
index 0000000..d81d5b0
--- /dev/null
+++ b/pineapple.stl