--- /dev/null
+ /* Created by exoticorn ( http://talk.maemo.org/showthread.php?t=37356 )
+ * edited and commented by André Bergner [endboss]
+ * edited by Javier for SDL_gles
+ *
+ * librariries needed: libgles2-dev, libsdl-gles1.2-dev, libsdl1.2-dev
+ *
+ * compile with: g++ -O2 -o simplegl `sdl-config --cflags --libs` -lSDL_gles -lGLESv2 simplegl.cc
+ */
+
+#include <iostream>
+using namespace std;
+
+#include <SDL.h>
+#include <SDL_gles.h>
+
+#include <cmath>
+#include <sys/time.h>
+
+#include <GLES2/gl2.h>
+
+static const char vertex_src[] = " \
+ attribute vec4 position; \
+ varying mediump vec2 pos; \
+ uniform vec4 offset; \
+ \
+ void main() \
+ { \
+ gl_Position = position + offset; \
+ pos = position.xy; \
+ } \
+ ";
+
+
+static const char fragment_src[] =
+ " \
+ varying mediump vec2 pos; \
+ uniform mediump float phase; \
+ \
+ void main() \
+ { \
+ gl_FragColor = vec4( 1., 0.9, 0.7, 1.0 ) * \
+ cos( 30.*sqrt(pos.x*pos.x + 1.5*pos.y*pos.y) \
+ + atan(pos.y,pos.x) - phase ); \
+ } \
+ ";
+
+static void print_shader_info_log(GLuint shader // handle to the shader
+ )
+{
+ GLint length, success;
+
+ glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &length);
+ if (length) {
+ char *buffer = new char[length];
+ glGetShaderInfoLog(shader, length, NULL, buffer);
+ cout << "shader info: " << buffer << flush;
+ delete[]buffer;
+ }
+
+ glGetShaderiv(shader, GL_COMPILE_STATUS, &success);
+ if (success != GL_TRUE) {
+ cerr << "failed to build shader" << endl;
+ exit(1);
+ }
+}
+
+static GLuint load_shader(const char *shader_source, GLenum type)
+{
+ GLuint shader = glCreateShader(type);
+
+ glShaderSource(shader, 1, &shader_source, NULL);
+ glCompileShader(shader);
+
+ print_shader_info_log(shader);
+
+ return shader;
+}
+
+static SDL_Surface *screen;
+static SDL_GLES_Context *context;
+
+GLfloat norm_x = 0.0, norm_y = 0.0,
+ offset_x = 0.0, offset_y = 0.0, p1_pos_x = 0.0, p1_pos_y = 0.0;
+
+GLint phase_loc, offset_loc, position_loc;
+
+bool update_pos = false;
+
+const float vertexArray[] = {
+ 0.0, 0.5, 0.0,
+ -0.5, 0.0, 0.0,
+ 0.0, -0.5, 0.0,
+ 0.5, 0.0, 0.0,
+ 0.0, 0.5, 0.0
+};
+
+
+void render()
+{
+ static float phase = 0;
+
+ //// draw
+ glClear(GL_COLOR_BUFFER_BIT);
+
+ glUniform1f(phase_loc, phase); // write the value of phase to the shaders phase
+ phase = fmodf(phase + 0.5f, 2.f * 3.141f); // and update the local variable
+
+ if (update_pos) { // if the position of the texture has changed due to user action
+ GLfloat old_offset_x = offset_x;
+ GLfloat old_offset_y = offset_y;
+
+ offset_x = norm_x - p1_pos_x;
+ offset_y = norm_y - p1_pos_y;
+
+ p1_pos_x = norm_x;
+ p1_pos_y = norm_y;
+
+ offset_x += old_offset_x;
+ offset_y += old_offset_y;
+
+ update_pos = false;
+ }
+
+ glUniform4f(offset_loc, offset_x, offset_y, 0.0, 0.0);
+
+ glVertexAttribPointer(position_loc, 3, GL_FLOAT, false, 0,
+ vertexArray);
+ glEnableVertexAttribArray(position_loc);
+ glDrawArrays(GL_TRIANGLE_STRIP, 0, 5);
+
+ SDL_GLES_SwapBuffers();
+}
+
+
+int main()
+{
+ SDL_Init(SDL_INIT_VIDEO);
+ SDL_GLES_Init(SDL_GLES_VERSION_2_0);
+ screen = SDL_SetVideoMode(0, 0, 16, SDL_SWSURFACE | SDL_FULLSCREEN);
+ SDL_WM_SetCaption("SimpleGL", "SimpleGL");
+ SDL_ShowCursor(SDL_DISABLE);
+ context = SDL_GLES_CreateContext();
+ SDL_GLES_MakeCurrent(context);
+
+ glClearColor(0.08, 0.06, 0.07, 1.0); // background color
+
+ GLuint vertexShader = load_shader(vertex_src, GL_VERTEX_SHADER); // load vertex shader
+ GLuint fragmentShader = load_shader(fragment_src, GL_FRAGMENT_SHADER); // load fragment shader
+
+ GLuint shaderProgram = glCreateProgram(); // create program object
+ glAttachShader(shaderProgram, vertexShader); // and attach both...
+ glAttachShader(shaderProgram, fragmentShader); // ... shaders to it
+
+ glLinkProgram(shaderProgram); // link the program
+ glUseProgram(shaderProgram); // and select it for usage
+
+ //// now get the locations (kind of handle) of the shaders variables
+ position_loc = glGetAttribLocation(shaderProgram, "position");
+ phase_loc = glGetUniformLocation(shaderProgram, "phase");
+ offset_loc = glGetUniformLocation(shaderProgram, "offset");
+ if (position_loc < 0 || phase_loc < 0 || offset_loc < 0) {
+ cerr << "Unable to get uniform location" << endl;
+ return 1;
+ }
+
+ const float window_width = screen->w, window_height = screen->h;
+
+ //// this is needed for time measuring --> frames per second
+ struct timezone tz;
+ timeval t1, t2;
+ gettimeofday(&t1, &tz);
+ int num_frames = 0;
+
+ bool quit = false;
+ while (!quit) { // the main loop
+ SDL_Event e;
+ GLfloat window_y, window_x;
+ while (SDL_PollEvent(&e)) { // check for events
+ switch(e.type) {
+ case SDL_MOUSEMOTION: // if mouse has moved
+ window_y = (window_height - e.motion.y) - window_height / 2.0;
+ norm_y = window_y / (window_height / 2.0);
+ window_x = e.motion.x - window_width / 2.0;
+ norm_x = window_x / (window_width / 2.0);
+ update_pos = true;
+ break;
+ case SDL_KEYDOWN:
+ case SDL_QUIT:
+ quit = true;
+ break;
+ }
+ }
+
+ render(); // now we finally put something on the screen
+
+ if (++num_frames % 100 == 0) { // update framerate counter
+ gettimeofday(&t2, &tz);
+ float dt =
+ t2.tv_sec - t1.tv_sec + (t2.tv_usec - t1.tv_usec) * 1e-6;
+ cout << "fps: " << num_frames / dt << endl;
+ num_frames = 0;
+ t1 = t2;
+ }
+ }
+
+ //// cleaning up...
+ SDL_GLES_Quit();
+ SDL_Quit();
+
+ return 0;
+}
+
projects / sdlhildon / commitdiff