move examples to examples directory

1 files changed, 162 insertions, 0 deletions

diff --git a/examples/example_opengl.cpp b/examples/example_opengl.cpp
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+/*
+LodePNG Examples
+
+Copyright (c) 2005-2012 Lode Vandevenne
+
+This software is provided 'as-is', without any express or implied
+warranty. In no event will the authors be held liable for any damages
+arising from the use of this software.
+
+Permission is granted to anyone to use this software for any purpose,
+including commercial applications, and to alter it and redistribute it
+freely, subject to the following restrictions:
+
+    1. The origin of this software must not be misrepresented; you must not
+    claim that you wrote the original software. If you use this software
+    in a product, an acknowledgment in the product documentation would be
+    appreciated but is not required.
+
+    2. Altered source versions must be plainly marked as such, and must not be
+    misrepresented as being the original software.
+
+    3. This notice may not be removed or altered from any source
+    distribution.
+*/
+
+//Compile command for Linux:
+//g++ lodepng.cpp example_opengl.cpp -lSDL -lGL -O3
+
+/*
+LodePNG OpenGL example. Decodes a PNG and shows it in OpenGL. PNG filename
+should be given as a command line parameter.
+
+It's written for the most basic old OpenGL version, and a correction for non
+power of two textures had to be added.
+
+Only very few lines on the sample are about loading the PNG. Most of the
+sample lines show a way to render a texture in 2D in OpenGL.
+
+No fancy 3D graphics are shown, it only shows the image statically. The sample
+shows LodePNG can be used to load PNG images as textures in OpenGL.
+*/
+
+#include "lodepng.h"
+
+#include <iostream>
+#include <SDL/SDL.h>
+#include <GL/gl.h>
+
+int main(int argc, char *argv[])
+{
+  if(argc < 2)
+  {
+    std::cout << "Please provide a filename." << std::endl;
+    return 1;
+  }
+  const char* filename = argv[1];
+
+  // Load file and decode image.
+  std::vector<unsigned char> image;
+  unsigned width, height;
+  unsigned error = lodepng::decode(image, width, height, filename);
+
+  // If there's an error, display it.
+  if(error != 0)
+  {
+    std::cout << "error " << error << ": " << lodepng_error_text(error) << std::endl;
+    return 1;
+  }
+  
+  // Here the PNG is loaded in "image". All the rest of the code is SDL and OpenGL stuff.
+
+  int screenw = width;
+  if(screenw > 1024) screenw = 1024;
+  int screenh = height;
+  if(screenh > 768) screenw = 768;
+
+  if(SDL_Init(SDL_INIT_VIDEO) < 0)
+  {
+    std::cout << "Error: Unable to init SDL: " << SDL_GetError() << std::endl;
+    return 1;
+  }
+  
+  SDL_Surface* scr = SDL_SetVideoMode(screenw, screenh, 32, SDL_OPENGL);
+
+  if(scr == 0)
+  {
+    std::cout << "Error: Unable to set video. SDL error message: " << SDL_GetError() << std::endl;
+    return 1;
+  }
+
+  // The official code for "Setting Your Raster Position to a Pixel Location" (i.e. set up a camera for 2D screen)
+  glViewport(0, 0, screenw, screenh);
+  glMatrixMode(GL_PROJECTION);
+  glLoadIdentity();
+  glOrtho(0, screenw, screenh, 0, -1, 1);
+  glMatrixMode(GL_MODELVIEW);
+  glLoadIdentity();
+
+  // Make some OpenGL properties better for 2D and enable alpha channel.
+  glDisable(GL_CULL_FACE);
+  glDisable(GL_DEPTH_TEST);
+  glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+  glEnable(GL_BLEND);
+  glDisable(GL_ALPHA_TEST);
+
+  if(glGetError() != GL_NO_ERROR)
+  {
+    std::cout << "Error initing GL" << std::endl;
+    return 1;
+  }
+  
+  // Texture size must be power of two for the primitive OpenGL version this is written for. Find next power of two.
+  size_t u2 = 1; while(u2 < width) u2 *= 2;
+  size_t v2 = 1; while(v2 < height) v2 *= 2;
+  // Ratio for power of two version compared to actual version, to render the non power of two image with proper size.
+  double u3 = (double)width / u2;
+  double v3 = (double)height / v2;
+
+  // Make power of two version of the image.
+  std::vector<unsigned char> image2(u2 * v2 * 4);
+  for(size_t y = 0; y < height; y++)
+  for(size_t x = 0; x < width; x++)
+  for(size_t c = 0; c < 4; c++)
+  {
+    image2[4 * u2 * y + 4 * x + c] = image[4 * width * y + 4 * x + c];
+  }
+  
+  // Enable the texture for OpenGL.
+  glEnable(GL_TEXTURE_2D);
+  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); //GL_NEAREST = no smoothing
+  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+  glTexImage2D(GL_TEXTURE_2D, 0, 4, u2, v2, 0, GL_RGBA, GL_UNSIGNED_BYTE, &image2[0]);
+  
+  bool done = false;
+  SDL_Event event = {0};
+  glColor4ub(255, 255, 255, 255);
+  
+  while(!done)
+  {
+    // Quit the loop when receiving quit event.
+    while(SDL_PollEvent(&event))
+    {
+      if(event.type == SDL_QUIT) done = 1;
+    }
+    
+    // Draw the texture on a quad, using u3 and v3 to correct non power of two texture size.
+    glBegin(GL_QUADS);
+      glTexCoord2d( 0,  0); glVertex2f(    0,      0);
+      glTexCoord2d(u3,  0); glVertex2f(width,      0);
+      glTexCoord2d(u3, v3); glVertex2f(width, height);
+      glTexCoord2d( 0, v3); glVertex2f(    0, height);
+    glEnd();
+    
+    // Redraw and clear screen.
+    SDL_GL_SwapBuffers();
+    glClearColor(0, 0, 0, 0);
+    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+    
+    //Limit frames per second, to not heat up the CPU and GPU too much.
+    SDL_Delay(16);
+  }
+}