From d28929a69b80f2efa0d0c957761ce81cf0e50f51 Mon Sep 17 00:00:00 2001
From: Matthias Schiffer <mschiffer@universe-factory.net>
Date: Tue, 2 Feb 2016 08:20:15 +0100
Subject: Add reload support (using inotify)

---
 Makefile   |   8 +++--
 glslview.c | 111 +++++++++++++++++++++++++++++++++++++++++++++++++++----------
 2 files changed, 99 insertions(+), 20 deletions(-)

diff --git a/Makefile b/Makefile
index 9e5304e..c79d1a5 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,11 @@
 all : glslview glslwrite
 
+USE_INOTIFY = -DUSE_INOTIFY
+
+CFLAGS = -O3 -Wall $(USE_INOTIFY)
+
 glslview : glslview.c
-	$(CC) -o $@ $^ -lSDL2 -lGL -lGLEW -Wall
+	$(CC) $(CFLAGS) -o $@ $^ -lSDL2 -lGL -lGLEW
 
 glslwrite : glslview.c
-	$(CC) -o $@ $^ -DGLSLWRITE -lSDL2 -lpng -lGL -lGLEW -Wall
+	$(CC) $(CFLAGS) -o $@ $^ -DGLSLWRITE -lSDL2 -lpng -lGL -lGLEW
diff --git a/glslview.c b/glslview.c
index 828ac3f..251a13b 100644
--- a/glslview.c
+++ b/glslview.c
@@ -1,8 +1,16 @@
+#include <fcntl.h>
+#include <limits.h>
 #include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <unistd.h>
 
+#ifdef USE_INOTIFY
+# include <sys/inotify.h>
+# include <sys/stat.h>
+# include <sys/types.h>
+#endif
+
 #ifdef GLSLWRITE
 # include <png.h>
 #endif
@@ -14,16 +22,27 @@
 
 
 #ifdef GLSLWRITE
+
 static unsigned frame_time = 0;
+
+#else
+
+static unsigned time_orig = 0;
+
+#ifdef USE_INOTIFY
+static int inotify_fd = -1;
 #endif
 
+#endif
 
+
+static char *filename;
 static GLint time_loc;
 static GLint res_loc;
 
 
-static char * readfile(const char *filename) {
-	FILE *f = fopen(filename, "r");
+static char * readfile(const char *name) {
+	FILE *f = fopen(name, "r");
 	if (!f)
 		return NULL;
 
@@ -74,15 +93,11 @@ static void printProgramInfoLog(GLuint obj) {
 	}
 }
 
-static void init(char *filename) {
-	glewInit();
-
-	glDisable(GL_DEPTH_TEST);
-
+static void load(void) {
 	char *shader = readfile(filename);
 	if (!shader) {
 		fprintf(stderr, "Error: unable to read '%s'\n", filename);
-		exit(1);
+		return;
 	}
 
 	GLuint frag = glCreateShader(GL_FRAGMENT_SHADER);
@@ -101,6 +116,43 @@ static void init(char *filename) {
 	res_loc = glGetUniformLocation(program, "res");
 
 	glUseProgram(program);
+
+	free(shader);
+	glDeleteShader(frag);
+	glDeleteProgram(program);
+}
+
+static void init(void) {
+#if defined(USE_INOTIFY) && !defined(GLSLWRITE)
+	inotify_fd = inotify_init();
+	if (inotify_fd < 0) {
+		fprintf(stderr, "unable to initialize inotify\n");
+		exit(1);
+	}
+
+	int watch = inotify_add_watch(inotify_fd, filename, IN_CLOSE_WRITE);
+	if (watch < 0) {
+		fprintf(stderr, "unable to watch '%s' for changes\n", filename);
+		exit(1);
+	}
+
+	fcntl(inotify_fd, F_SETFL, fcntl(inotify_fd, F_GETFL)|O_NONBLOCK);
+
+#endif
+
+	glewInit();
+	glDisable(GL_DEPTH_TEST);
+	glColor4f(0, 0, 0, 0);
+
+	load();
+}
+
+static void check_reload(void) {
+#if defined(USE_INOTIFY) && !defined(GLSLWRITE)
+	char buf[sizeof(struct inotify_event) + NAME_MAX + 1];
+	if (read(inotify_fd, buf, sizeof(buf)) > 0)
+		load();
+#endif
 }
 
 #ifdef GLSLWRITE
@@ -159,7 +211,7 @@ static void render(int width, int height) {
 #ifdef GLSLWRITE
 	glUniform1f(time_loc, frame_time);
 #else
-	glUniform1f(time_loc, SDL_GetTicks());
+	glUniform1f(time_loc, SDL_GetTicks() - time_orig);
 #endif
 	glUniform2f(res_loc, width, height);
 
@@ -177,8 +229,6 @@ static void render(int width, int height) {
 
 
 int main(int argc, char *argv[]) {
-	bool running = true;
-
 #ifdef GLSLWRITE
 	if (argc != 3) {
 		fprintf(stderr, "Usage: glslwrite <shader> <output directory>\n");
@@ -186,7 +236,7 @@ int main(int argc, char *argv[]) {
 	}
 #else
 	if (argc != 2) {
-		fprintf(stderr, "Usage: glslview <shader> <output directory>\n");
+		fprintf(stderr, "Usage: glslview <shader>\n");
 		exit(1);
 	}
 #endif
@@ -199,20 +249,40 @@ int main(int argc, char *argv[]) {
 	SDL_GL_SetAttribute(SDL_GL_ALPHA_SIZE, 8);
 
 	SDL_Window *window = SDL_CreateWindow("glslwrite", 0, 0, 800, 800, SDL_WINDOW_OPENGL|SDL_WINDOW_RESIZABLE);
-	SDL_GL_CreateContext(window);
+	SDL_GLContext ctx = SDL_GL_CreateContext(window);
 
-	init(argv[1]);
+	filename = argv[1];
+	init();
 
-	while (running) {
+	while (true) {
 		SDL_Event e;
 
-		while( SDL_PollEvent(&e)) {
-			if(e.type == SDL_QUIT) {
-				running = false;
+		while (SDL_PollEvent(&e)) {
+			switch (e.type) {
+			case SDL_KEYDOWN:
+				switch (e.key.keysym.sym) {
+				case SDLK_ESCAPE:
+					goto quit;
+
+#ifndef GLSLWRITE
+				case SDLK_l:
+					load();
+					break;
+
+				case SDLK_r:
+					time_orig = SDL_GetTicks();
+					break;
+#endif
+				}
 				break;
+
+			case SDL_QUIT:
+				goto quit;
 			}
 		}
 
+		check_reload();
+
 		int width, height;
 		SDL_GetWindowSize(window, &width, &height);
 
@@ -224,5 +294,10 @@ int main(int argc, char *argv[]) {
 #endif
 	}
 
+ quit:
+	SDL_GL_DeleteContext(ctx);
+	SDL_DestroyWindow(window);
+	SDL_Quit();
+
 	return 0;
 }
-- 
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