From 3fb09ad03aa464d21b0f75ba1e4bc1bdcedb7d5f Mon Sep 17 00:00:00 2001
From: Sam Nystrom <sam@samnystrom.dev>
Date: Wed, 14 Feb 2024 15:38:50 +0000
Subject: Move rendering code into function

---
 pineapple.c | 75 ++++++++++++++++++++++++++++++++++++++++---------------------
 1 file changed, 50 insertions(+), 25 deletions(-)

diff --git a/pineapple.c b/pineapple.c
index 043904f..772e7b6 100644
--- a/pineapple.c
+++ b/pineapple.c
@@ -33,6 +33,13 @@ struct __attribute__((__packed__)) triangle_raw {
 	uint16_t _attr_count; /* unused */
 };
 
+struct camera {
+	vec3 pos;
+	float theta;
+	float phi;
+	float fov;
+};
+
 static inline vec3
 vadd(vec3 a, vec3 b)
 {
@@ -96,6 +103,37 @@ ray_triangle_intersect(vec3 P, vec3 d, struct triangle tri)
 	return NAN;
 }
 
+static void
+render_frame(struct camera cam, vec3 light,
+             const struct triangle *triangles, uint32_t len,
+             float *pixels, uint32_t width, uint32_t height)
+{
+	for (int h = height - 1; h >= 0; --h) {
+		for (uint32_t w = 0; w < width; ++w) {
+			float theta = cam.theta - cam.fov/2.0 + cam.fov/height*h;
+			float phi = cam.phi - cam.fov/2.0 + cam.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(cam.pos, dir, triangles[i]);
+				if (d != NAN && fabs(d) < fabs(shortest)) {
+					shortest = d;
+					shortest_norm = triangles[i].n;
+				}
+			}
+
+			pixels[w*width + h] = 0.0;
+			if (shortest != INFINITY) {
+				float light_angle = acosf(dot(shortest_norm, light) / magnitude(shortest_norm) / magnitude(light));
+				pixels[w*width + h] = light_angle / PI;
+			}
+		}
+	}
+}
+
 int
 main(int argc, char *argv[])
 {
@@ -135,10 +173,12 @@ main(int argc, char *argv[])
 	}
 	if (verbosity >= 1) fprintf(stderr, "finished reading STL: %d facets\n", len);
 
-	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;
+	struct camera cam = {
+		.pos = { -70.0, 60.0, 60.0 },
+		.phi = PI * 0.8,
+		.theta = PI * 0.5,
+		.fov = 80.0 * PI / 180.0
+	};
 	vec3 light = { 0.0, 0.0, -1.0 };
 
 	if (mode == FARBFELD) {
@@ -149,29 +189,13 @@ main(int argc, char *argv[])
 		fwrite(&hbe, 1, 4, stdout);
 	}
 
+	float *pixels = calloc(sizeof(float), width * height);
+	if (!pixels) diesys(111, "fatal: unable to allocate enough memory for pixel buffer");
+	render_frame(cam, light, triangles, len, pixels, width, height);
+
 	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].n;
-				}
-			}
-
-			float brightness = 0.0;
-			if (shortest != INFINITY) {
-				float light_angle = acosf(dot(shortest_norm, light) / magnitude(shortest_norm) / magnitude(light));
-				brightness = light_angle / PI;
-			}
+			float brightness = pixels[w*width + h];
 			if (mode == ASCII) {
 				printf("%c", ASCII_CHARS[strlen(ASCII_CHARS) - 1 - (int)(brightness * strlen(ASCII_CHARS))]);
 			} else if (mode == FARBFELD) {
@@ -182,6 +206,7 @@ main(int argc, char *argv[])
 		}
 		if (mode == ASCII) printf("\n");
 	}
+	free(pixels);
 
 	return 0;
 }
\ No newline at end of file
-- 
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