From f81f0074c0db900cbc44113d457a2395d3a55fd1 Mon Sep 17 00:00:00 2001
From: Matthias Schiffer <mschiffer@universe-factory.net>
Date: Tue, 2 Feb 2016 09:00:05 +0100
Subject: Add support for changing the speed

---
 Makefile   |  5 +++--
 glslview.c | 67 ++++++++++++++++++++++++++++++++++++++++++++++++++------------
 2 files changed, 57 insertions(+), 15 deletions(-)

diff --git a/Makefile b/Makefile
index c79d1a5..11a990e 100644
--- a/Makefile
+++ b/Makefile
@@ -3,9 +3,10 @@ all : glslview glslwrite
 USE_INOTIFY = -DUSE_INOTIFY
 
 CFLAGS = -O3 -Wall $(USE_INOTIFY)
+LIBS = -lSDL2 -lGL -lGLEW -lm
 
 glslview : glslview.c
-	$(CC) $(CFLAGS) -o $@ $^ -lSDL2 -lGL -lGLEW
+	$(CC) $(CFLAGS) -o $@ $^ $(LIBS)
 
 glslwrite : glslview.c
-	$(CC) $(CFLAGS) -o $@ $^ -DGLSLWRITE -lSDL2 -lpng -lGL -lGLEW
+	$(CC) $(CFLAGS) -DGLSLWRITE -o $@ $^ $(LIBS) -lpng
diff --git a/glslview.c b/glslview.c
index b443522..6918fa0 100644
--- a/glslview.c
+++ b/glslview.c
@@ -1,5 +1,6 @@
 #include <fcntl.h>
 #include <limits.h>
+#include <math.h>
 #include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
@@ -27,7 +28,9 @@ static unsigned frame_time = 0;
 
 #else
 
-static unsigned time_orig = 0;
+static float speed = 1.0;
+static float current_time = 0;
+static unsigned previous_ticks = 0;
 
 #ifdef USE_INOTIFY
 static int inotify_fd = -1;
@@ -222,10 +225,19 @@ static void render(int width, int height) {
 	glViewport(0, 0, (GLsizei)width, (GLsizei)height);
 
 #ifdef GLSLWRITE
+
 	glUniform1f(time_loc, frame_time);
+
 #else
-	glUniform1f(time_loc, SDL_GetTicks() - time_orig);
+
+	unsigned ticks = SDL_GetTicks();
+	current_time += speed * (ticks - previous_ticks);
+	previous_ticks = ticks;
+
+	glUniform1f(time_loc, current_time);
+
 #endif
+
 	glUniform2f(res_loc, width, height);
 
 	glBegin(GL_QUADS);
@@ -240,6 +252,35 @@ static void render(int width, int height) {
 #endif
 }
 
+#ifndef GLSLWRITE
+static void handle_input(const char *input) {
+	for (; *input; input++) {
+		switch (*input) {
+		case 'l':
+#ifdef USE_INOTIFY
+			reset_watch();
+#endif
+			load();
+			break;
+
+		case 'r':
+			current_time = 0;
+			break;
+
+		case '+':
+			speed *= 1.1;
+			break;
+
+		case '-':
+			speed /= 1.1;
+			break;
+
+		case '=':
+			speed = 1.0;
+		}
+	}
+}
+#endif
 
 int main(int argc, char *argv[]) {
 #ifdef GLSLWRITE
@@ -267,6 +308,8 @@ int main(int argc, char *argv[]) {
 	filename = argv[1];
 	init();
 
+	SDL_StartTextInput();
+
 	while (true) {
 		SDL_Event e;
 
@@ -276,21 +319,18 @@ int main(int argc, char *argv[]) {
 				switch (e.key.keysym.sym) {
 				case SDLK_ESCAPE:
 					goto quit;
+				}
+				break;
 
 #ifndef GLSLWRITE
-				case SDLK_l:
-#ifdef USE_INOTIFY
-					reset_watch();
-#endif
-					load();
-					break;
+			case SDL_TEXTINPUT:
+				handle_input(e.text.text);
+				break;
 
-				case SDLK_r:
-					time_orig = SDL_GetTicks();
-					break;
-#endif
-				}
+			case SDL_MOUSEWHEEL:
+				speed /= pow(1.1, e.wheel.y);
 				break;
+#endif
 
 			case SDL_QUIT:
 				goto quit;
@@ -311,6 +351,7 @@ int main(int argc, char *argv[]) {
 	}
 
  quit:
+	SDL_StopTextInput();
 	SDL_GL_DeleteContext(ctx);
 	SDL_DestroyWindow(window);
 	SDL_Quit();
-- 
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