penrose

commit 1bfd507a21918e7a38218c97c47be528fd9712ed
parent 3e9f96ebcd5b958ce2fb6d4010591764f9733d7c
Author: mpizzzle <m@michaelpercival.xyz>
Date:   Sat, 14 Nov 2020 20:05:25 +0000

successfully writing png image (almost, weird artifact in image)

Diffstat:
M
penrose.cpp
 | 
30
+++++++++++++++---------------
M
png_writer.cpp
 | 
45
++++++++++++++++++++++++++++++++++++---------
M
png_writer.hpp
 | 
4
+++-

3 files changed, 54 insertions(+), 25 deletions(-)
diff --git a/penrose.cpp b/penrose.cpp
@@ -14,13 +14,15 @@
 #include <vector>
 #include <random>
 
+#include <png.h>
+
 #include "shader.hpp"
 #include "png_writer.hpp"
 
 static const uint32_t window_w = 1920 * 4;
 static const uint32_t window_h = 1080 * 4;
 static const uint32_t depth = 10;      //recursion depth
-        static const bool p2 = true;          //tiling type (p2, p3)
+static const bool p2 = false;          //tiling type (p2, p3)
 static const float line_w = 2.0f;      //line width
 
 static const float phi = 1.0 / ((1.0 + sqrt(5.0)) / 2);
@@ -180,23 +182,21 @@ int main() {
         glfwPollEvents();
     }
 
-    //int width, height;
 
-    //glfwGetFramebufferSize(window, &width, &height);
-    //std::cout << "width: "<< width << " height: " << height << std::endl;
-    //GLsizei nrChannels = 4;
-    //GLsizei stride = nrChannels * width;
-    //stride += (stride % 4) ? (4 - stride % 4) : 0;
-    //GLsizei bufferSize = stride * height;
-    //std::vector<char> buffer(bufferSize);
-    //glPixelStorei(GL_PACK_ALIGNMENT, 4);
-    //glReadBuffer(GL_FRONT);
-    //glReadPixels(0, 0, width, height, GL_RGBA, GL_UNSIGNED_BYTE, buffer.data());
+    glPixelStorei(GL_PACK_ALIGNMENT, 4);
+    glReadBuffer(GL_FRONT);
+
+    int frame_w, frame_h;
+    glfwGetFramebufferSize(window, &frame_w, &frame_h);
 
-    //stbi_flip_vertically_on_write(true);
-    //stbi_write_png(filepath, width, height, nrChannels, buffer.data(), stride);
+    png_bytep* row_pointers = (png_bytep*) malloc(sizeof(unsigned char) * frame_h);
+
+    for (unsigned int yy = 0; yy < frame_h; ++yy) {
+        row_pointers[yy] = (png_byte*) malloc((4 * sizeof(png_byte)) * frame_w);
+        glReadPixels(0, yy, frame_w, 1, GL_RGBA, GL_UNSIGNED_BYTE, row_pointers[yy]);
+    }
 
-    //PngWriter::write_png_file("test.png", window_w, window_h, nullptr);
+    PngWriter::write_png_file("test.png", frame_w, frame_h, row_pointers);
 
     return 0;
 }
diff --git a/png_writer.cpp b/png_writer.cpp
@@ -14,38 +14,65 @@
 
 #include "png_writer.hpp"
 
-void PngWriter::write_png_file(std::string file_name, int width, int height, std::byte* row_pointers) {
+void abort_(const char * s, ...)
+{
+    va_list args;
+    va_start(args, s);
+    vfprintf(stderr, s, args);
+    fprintf(stderr, "n");
+    va_end(args);
+    abort();
+}
+
+void PngWriter::write_png_file(std::string file_name, int width, int height, png_bytep* row_pointers) {
     png_structp png_ptr;
     png_infop info_ptr;
 
     /* create file */
     FILE *fp = fopen(file_name.c_str(), "wb");
+    if (!fp)
+        abort_("[write_png_file] File %s could not be opened for writing", file_name.c_str());
 
+    /* initialize stuff */
     png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
+
+    if (!png_ptr)
+        abort_("[write_png_file] png_create_write_struct failed");
+
     info_ptr = png_create_info_struct(png_ptr);
-    setjmp(png_jmpbuf(png_ptr));
+    if (!info_ptr)
+        abort_("[write_png_file] png_create_info_struct failed");
+
+    if (setjmp(png_jmpbuf(png_ptr)))
+        abort_("[write_png_file] Error during init_io");
+
     png_init_io(png_ptr, fp);
 
-    setjmp(png_jmpbuf(png_ptr));
+    /* write header */
+    if (setjmp(png_jmpbuf(png_ptr)))
+        abort_("[write_png_file] Error during writing header");
 
     png_set_IHDR(png_ptr, info_ptr, width, height,
-             16, PNG_COLOR_TYPE_RGBA, PNG_INTERLACE_NONE,
+             8, PNG_COLOR_TYPE_RGBA, PNG_INTERLACE_NONE,
              PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
 
     png_write_info(png_ptr, info_ptr);
 
-    setjmp(png_jmpbuf(png_ptr));
+    /* write bytes */
+    if (setjmp(png_jmpbuf(png_ptr)))
+        abort_("[write_png_file] Error during writing bytes");
 
-    png_write_image(png_ptr, (png_bytep *)row_pointers);
+    png_write_image(png_ptr, row_pointers);
 
-    setjmp(png_jmpbuf(png_ptr));
+    /* end write */
+    if (setjmp(png_jmpbuf(png_ptr)))
+        abort_("[write_png_file] Error during end of write");
 
     png_write_end(png_ptr, NULL);
 
     /* cleanup heap allocation */
-    //for (uint32_t y = 0; y < height; y++)
+    //for (y=0; y<height; y++)
     //    free(row_pointers[y]);
-
     //free(row_pointers);
 
     fclose(fp);
diff --git a/png_writer.hpp b/png_writer.hpp
@@ -5,7 +5,9 @@
 
 #include <string>
 
+#include <png.h>
+
 class PngWriter {
 public:
-    static void write_png_file(std::string file_name, int width, int height, std::byte* row_pointers);
+    static void write_png_file(std::string file_name, int width, int height, png_bytep* row_pointers);
 };