From 984b02a874d77d9b79a80cc09f6b9b56dd12ca31 Mon Sep 17 00:00:00 2001
From: Matthias Schiffer <mschiffer@universe-factory.net>
Date: Mon, 1 Feb 2016 14:39:58 +0100
Subject: Unify glwlview and glslwrite code

---
 glslview.c | 104 ++++++++++++++++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 89 insertions(+), 15 deletions(-)

(limited to 'glslview.c')

diff --git a/glslview.c b/glslview.c
index c78bd7d..940c30d 100644
--- a/glslview.c
+++ b/glslview.c
@@ -1,16 +1,25 @@
 #include <stdbool.h>
+#include <stdint.h>
 #include <stdio.h>
 #include <unistd.h>
 
+#ifdef GLSLWRITE
+# include <png.h>
+#endif
+
 #include <GL/glew.h>
 
 #include <SDL2/SDL.h>
 #include <SDL2/SDL_opengl.h>
 
 
+#ifdef GLSLWRITE
+static unsigned frame_time = 0;
+#endif
+
 
-static GLint time;
-static GLint res;
+static GLint time_loc;
+static GLint res_loc;
 
 
 static char * readfile(const char *filename) {
@@ -88,22 +97,71 @@ static void init(char *filename) {
         printProgramInfoLog(program);
 
         glBindFragDataLocation(program, 0, "fragColor");
-        time = glGetUniformLocation(program, "time");
-        res = glGetUniformLocation(program, "res");
+        time_loc = glGetUniformLocation(program, "time");
+        res_loc = glGetUniformLocation(program, "res");
 
         glUseProgram(program);
+}
 
+#ifdef GLSLWRITE
+static void savePNG(int width, int height, const char *output_dir) {
+        uint8_t pixels[width*height*4];
+        glReadPixels(0, 0, width, height, GL_RGBA, GL_UNSIGNED_INT_8_8_8_8, pixels);
 
-}
+        char filename[strlen(output_dir) + 20];
+        snprintf(filename, sizeof(filename), "%s/%010u.png", output_dir, frame_time);
+
+        FILE *f = fopen(filename, "wb");
+	if (!f) {
+                fprintf(stderr, "unable to open PNG file\n");
+                exit(1);
+        }
+
+	png_structp png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
+	if (!png_ptr) {
+                fprintf(stderr, "unable to open PNG file\n");
+                exit(1);
+        }
+
+        png_set_swap_alpha(png_ptr);
+
+	png_infop info_ptr = png_create_info_struct(png_ptr);
+	if (!info_ptr) {
+		fprintf(stderr, "unable to create PNG info struct\n");
+                exit(1);
+	}
+
+	if (setjmp(png_jmpbuf(png_ptr))) {
+		fprintf(stderr, "unable to write PNG file\n");
+                exit(1);
+	}
+
+	png_init_io(png_ptr, f);
+
+	png_set_IHDR(png_ptr, info_ptr, width, height, 8, PNG_COLOR_TYPE_RGB_ALPHA,
+		     PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
+
+	uint8_t *row_pointers[height];
+	for (size_t i = 0; i < height; i++)
+		row_pointers[i] = &pixels[4*i*width];
 
-static void render(SDL_Window *window) {
-        int width, height;
-        SDL_GetWindowSize(window, &width, &height);
+	png_set_rows(png_ptr, info_ptr, row_pointers);
+	png_write_png(png_ptr, info_ptr, PNG_TRANSFORM_IDENTITY, NULL);
 
+	png_destroy_write_struct(&png_ptr, &info_ptr);
+	fclose(f);
+}
+#endif
+
+static void render(int width, int height) {
 	glViewport(0, 0, (GLsizei)width, (GLsizei)height);
 
-        glUniform1f(time, SDL_GetTicks());
-        glUniform2f(res, width, height);
+#ifdef GLSLWRITE
+        glUniform1f(time_loc, frame_time);
+#else
+        glUniform1f(time_loc, SDL_GetTicks());
+#endif
+        glUniform2f(res_loc, width, height);
 
 	glBegin(GL_QUADS);
 	glVertex2f(-1, -1);
@@ -112,21 +170,30 @@ static void render(SDL_Window *window) {
 	glVertex2f(-1, 1);
 	glEnd();
 
-	SDL_GL_SwapWindow(window);
+#ifdef GLSLWRITE
+        frame_time += 20;
+#endif
 }
 
 
 int main(int argc, char *argv[]) {
 	bool running = true;
 
+#ifdef GLSLWRITE
+        if (argc != 3) {
+                fprintf(stderr, "Usage: glslwrite <shader> <output directory>\n");
+                exit(1);
+        }
+#else
         if (argc != 2) {
-                fprintf(stderr, "Usage: glslview <shader>\n");
+                fprintf(stderr, "Usage: glslview <shader> <output directory>\n");
                 exit(1);
         }
+#endif
 
 	SDL_Init(SDL_INIT_VIDEO);
 
-	SDL_Window *window = SDL_CreateWindow("glslview", 0, 0, 800, 800, SDL_WINDOW_OPENGL|SDL_WINDOW_RESIZABLE);
+	SDL_Window *window = SDL_CreateWindow("glslwrite", 0, 0, 800, 800, SDL_WINDOW_OPENGL|SDL_WINDOW_RESIZABLE);
         SDL_GL_CreateContext(window);
 
         init(argv[1]);
@@ -141,8 +208,15 @@ int main(int argc, char *argv[]) {
 			}
 		}
 
-		render(window);
-                //usleep(1);
+                int width, height;
+                SDL_GetWindowSize(window, &width, &height);
+
+		render(width, height);
+        	SDL_GL_SwapWindow(window);
+
+#ifdef GLSLWRITE
+                savePNG(width, height, argv[2]);
+#endif
 	}
 
 	return 0;
-- 
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