/**************************************************************************
 * 
 * Copyright 2008 Tungsten Graphics, Inc., Cedar Park, Texas.
 * All Rights Reserved.
 *
 **************************************************************************/

/*
 * Draw a triangle with X/EGL and OpenGL ES 2.x
 */

#define USE_FULL_GL 0



#include <assert.h>
#include <math.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/keysym.h>
#if USE_FULL_GL
#include <GL/gl.h>  /* use full OpenGL */
#else
#include <GLES2/gl2.h>  /* use OpenGL ES 2.x */
#endif
#include <EGL/egl.h>


#define FLOAT_TO_FIXED(X)   ((X) * 65535.0)



static GLfloat view_rotx = 0.0, view_roty = 0.0;

static GLint u_matrix = -1;
static GLint attr_pos = 0, attr_color = 1;


static void
make_z_rot_matrix(GLfloat angle, GLfloat *m)
{
   float c = cos(angle * M_PI / 180.0);
   float s = sin(angle * M_PI / 180.0);
   int i;
   for (i = 0; i < 16; i++)
      m[i] = 0.0;
   m[0] = m[5] = m[10] = m[15] = 1.0;

   m[0] = c;
   m[1] = s;
   m[4] = -s;
   m[5] = c;
}

static void
make_scale_matrix(GLfloat xs, GLfloat ys, GLfloat zs, GLfloat *m)
{
   int i;
   for (i = 0; i < 16; i++)
      m[i] = 0.0;
   m[0] = xs;
   m[5] = ys;
   m[10] = zs;
   m[15] = 1.0;
}


static void
mul_matrix(GLfloat *prod, const GLfloat *a, const GLfloat *b)
{
#define A(row,col)  a[(col<<2)+row]
#define B(row,col)  b[(col<<2)+row]
#define P(row,col)  p[(col<<2)+row]
   GLfloat p[16];
   GLint i;
   for (i = 0; i < 4; i++) {
      const GLfloat ai0=A(i,0),  ai1=A(i,1),  ai2=A(i,2),  ai3=A(i,3);
      P(i,0) = ai0 * B(0,0) + ai1 * B(1,0) + ai2 * B(2,0) + ai3 * B(3,0);
      P(i,1) = ai0 * B(0,1) + ai1 * B(1,1) + ai2 * B(2,1) + ai3 * B(3,1);
      P(i,2) = ai0 * B(0,2) + ai1 * B(1,2) + ai2 * B(2,2) + ai3 * B(3,2);
      P(i,3) = ai0 * B(0,3) + ai1 * B(1,3) + ai2 * B(2,3) + ai3 * B(3,3);
   }
   memcpy(prod, p, sizeof(p));
#undef A
#undef B
#undef PROD
}


static void
draw(void)
{
   static const GLfloat verts[3][2] = {
      { -1, -1 },
      {  1, -1 },
      {  0,  1 }
   };
   static const GLfloat colors[3][3] = {
      { 1, 0, 0 },
      { 0, 1, 0 },
      { 0, 0, 1 }
   };
   GLfloat mat[16], rot[16], scale[16];

   /* Set modelview/projection matrix */
   make_z_rot_matrix(view_rotx, rot);
   make_scale_matrix(0.5, 0.5, 0.5, scale);
   mul_matrix(mat, rot, scale);
   glUniformMatrix4fv(u_matrix, 1, GL_FALSE, mat);

   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

   {
      glVertexAttribPointer(attr_pos, 2, GL_FLOAT, GL_FALSE, 0, verts);
      glVertexAttribPointer(attr_color, 3, GL_FLOAT, GL_FALSE, 0, colors);
      glEnableVertexAttribArray(attr_pos);
      glEnableVertexAttribArray(attr_color);

      glDrawArrays(GL_TRIANGLES, 0, 3);

      glDisableVertexAttribArray(attr_pos);
      glDisableVertexAttribArray(attr_color);
   }
}


/* new window size or exposure */
static void
reshape(int width, int height)
{
   glViewport(0, 0, (GLint) width, (GLint) height);
}


static void
create_shaders(void)
{
   static const char *fragShaderText =
      "varying vec4 v_color;\n"
      "void main() {\n"
      "   gl_FragColor = v_color;\n"
      "}\n";
   static const char *vertShaderText =
      "uniform mat4 modelviewProjection;\n"
      "attribute vec4 pos;\n"
      "attribute vec4 color;\n"
      "varying vec4 v_color;\n"
      "void main() {\n"
      "   gl_Position = modelviewProjection * pos;\n"
      "   v_color = color;\n"
      "}\n";

   GLuint fragShader, vertShader, program;
   GLint stat;

   fragShader = glCreateShader(GL_FRAGMENT_SHADER);
   glShaderSource(fragShader, 1, (const char **) &fragShaderText, NULL);
   glCompileShader(fragShader);
   glGetShaderiv(fragShader, GL_COMPILE_STATUS, &stat);
   if (!stat) {
      printf("Error: fragment shader did not compile!\n");
      exit(1);
   }

   vertShader = glCreateShader(GL_VERTEX_SHADER);
   glShaderSource(vertShader, 1, (const char **) &vertShaderText, NULL);
   glCompileShader(vertShader);
   glGetShaderiv(vertShader, GL_COMPILE_STATUS, &stat);
   if (!stat) {
      printf("Error: vertex shader did not compile!\n");
      exit(1);
   }

   program = glCreateProgram();
   glAttachShader(program, fragShader);
   glAttachShader(program, vertShader);
   glLinkProgram(program);

   glGetProgramiv(program, GL_LINK_STATUS, &stat);
   if (!stat) {
      char log[1000];
      GLsizei len;
      glGetProgramInfoLog(program, 1000, &len, log);
      printf("Error: linking:\n%s\n", log);
      exit(1);
   }

   glUseProgram(program);

   if (1) {
      /* test setting attrib locations */
      glBindAttribLocation(program, attr_pos, "pos");
      glBindAttribLocation(program, attr_color, "color");
      glLinkProgram(program);  /* needed to put attribs into effect */
   }
   else {
      /* test automatic attrib locations */
      attr_pos = glGetAttribLocation(program, "pos");
      attr_color = glGetAttribLocation(program, "color");
   }

   u_matrix = glGetUniformLocation(program, "modelviewProjection");
   printf("Uniform modelviewProjection at %d\n", u_matrix);
   printf("Attrib pos at %d\n", attr_pos);
   printf("Attrib color at %d\n", attr_color);
}


static void
init(void)
{
   typedef void (*proc)();

#if 1 /* test code */
   proc p = eglGetProcAddress("glMapBufferOES");
   assert(p);
#endif

   glClearColor(0.4, 0.4, 0.4, 0.0);

   create_shaders();
}


/*
 * Create an RGB, double-buffered X window.
 * Return the window and context handles.
 */
static void
make_x_window(Display *x_dpy, EGLDisplay egl_dpy,
              const char *name,
              int x, int y, int width, int height,
              Window *winRet,
              EGLContext *ctxRet,
              EGLSurface *surfRet)
{
   static const EGLint attribs[] = {
      EGL_RED_SIZE, 1,
      EGL_GREEN_SIZE, 1,
      EGL_BLUE_SIZE, 1,
      EGL_DEPTH_SIZE, 1,
      EGL_NONE
   };
   static const EGLint ctx_attribs[] = {
      EGL_CONTEXT_CLIENT_VERSION, 2,
      EGL_NONE
   };
   int scrnum;
   XSetWindowAttributes attr;
   unsigned long mask;
   Window root;
   Window win;
   XVisualInfo *visInfo, visTemplate;
   int num_visuals;
   EGLContext ctx;
   EGLConfig config;
   EGLint num_configs;
   EGLint vid;

   scrnum = DefaultScreen( x_dpy );
   root = RootWindow( x_dpy, scrnum );

   if (!eglChooseConfig( egl_dpy, attribs, &config, 1, &num_configs)) {
      printf("Error: couldn't get an EGL visual config\n");
      exit(1);
   }

   assert(config);
   assert(num_configs > 0);

   if (!eglGetConfigAttrib(egl_dpy, config, EGL_NATIVE_VISUAL_ID, &vid)) {
      printf("Error: eglGetConfigAttrib() failed\n");
      exit(1);
   }

   /* The X window visual must match the EGL config */
   visTemplate.visualid = vid;
   visInfo = XGetVisualInfo(x_dpy, VisualIDMask, &visTemplate, &num_visuals);
   if (!visInfo) {
      printf("Error: couldn't get X visual\n");
      exit(1);
   }

   /* window attributes */
   attr.background_pixel = 0;
   attr.border_pixel = 0;
   attr.colormap = XCreateColormap( x_dpy, root, visInfo->visual, AllocNone);
   attr.event_mask = StructureNotifyMask | ExposureMask | KeyPressMask;
   mask = CWBackPixel | CWBorderPixel | CWColormap | CWEventMask;

   win = XCreateWindow( x_dpy, root, 0, 0, width, height,
		        0, visInfo->depth, InputOutput,
		        visInfo->visual, mask, &attr );

   /* set hints and properties */
   {
      XSizeHints sizehints;
      sizehints.x = x;
      sizehints.y = y;
      sizehints.width  = width;
      sizehints.height = height;
      sizehints.flags = USSize | USPosition;
      XSetNormalHints(x_dpy, win, &sizehints);
      XSetStandardProperties(x_dpy, win, name, name,
                              None, (char **)NULL, 0, &sizehints);
   }

#if USE_FULL_GL /* XXX fix this when eglBindAPI() works */
   eglBindAPI(EGL_OPENGL_API);
#else
   eglBindAPI(EGL_OPENGL_ES_API);
#endif

   ctx = eglCreateContext(egl_dpy, config, EGL_NO_CONTEXT, ctx_attribs );
   if (!ctx) {
      printf("Error: eglCreateContext failed\n");
      exit(1);
   }

   /* test eglQueryContext() */
   {
      EGLint val;
      eglQueryContext(egl_dpy, ctx, EGL_CONTEXT_CLIENT_VERSION, &val);
      assert(val == 2);
   }

   *surfRet = eglCreateWindowSurface(egl_dpy, config, win, NULL);
   if (!*surfRet) {
      printf("Error: eglCreateWindowSurface failed\n");
      exit(1);
   }

   {
      EGLint val;
      eglQuerySurface(egl_dpy, *surfRet, EGL_WIDTH, &val);
      assert(val == width);
      eglQuerySurface(egl_dpy, *surfRet, EGL_HEIGHT, &val);
      assert(val == height);
      eglQuerySurface(egl_dpy, *surfRet, EGL_SURFACE_TYPE, &val);
      assert(val == EGL_WINDOW_BIT);
   }

   XFree(visInfo);

   *winRet = win;
   *ctxRet = ctx;
}


static void
event_loop(Display *dpy, Window win,
           EGLDisplay egl_dpy, EGLSurface egl_surf)
{
   while (1) {
      int redraw = 0;
      XEvent event;

      XNextEvent(dpy, &event);

      switch (event.type) {
      case Expose:
         redraw = 1;
         break;
      case ConfigureNotify:
         reshape(event.xconfigure.width, event.xconfigure.height);
         break;
      case KeyPress:
         {
            char buffer[10];
            int r, code;
            code = XLookupKeysym(&event.xkey, 0);
            if (code == XK_Left) {
               view_roty += 5.0;
            }
            else if (code == XK_Right) {
               view_roty -= 5.0;
            }
            else if (code == XK_Up) {
               view_rotx += 5.0;
            }
            else if (code == XK_Down) {
               view_rotx -= 5.0;
            }
            else {
               r = XLookupString(&event.xkey, buffer, sizeof(buffer),
                                 NULL, NULL);
               if (buffer[0] == 27) {
                  /* escape */
                  return;
               }
            }
         }
         redraw = 1;
         break;
      default:
         ; /*no-op*/
      }

      if (redraw) {
         draw();
         eglSwapBuffers(egl_dpy, egl_surf);
      }
   }
}


static void
usage(void)
{
   printf("Usage:\n");
   printf("  -display <displayname>  set the display to run on\n");
   printf("  -info                   display OpenGL renderer info\n");
}
 

int
main(int argc, char *argv[])
{
   const int winWidth = 300, winHeight = 300;
   Display *x_dpy;
   Window win;
   EGLSurface egl_surf;
   EGLContext egl_ctx;
   EGLDisplay egl_dpy;
   char *dpyName = NULL;
   GLboolean printInfo = GL_FALSE;
   EGLint egl_major, egl_minor;
   int i;
   const char *s;

   for (i = 1; i < argc; i++) {
      if (strcmp(argv[i], "-display") == 0) {
         dpyName = argv[i+1];
         i++;
      }
      else if (strcmp(argv[i], "-info") == 0) {
         printInfo = GL_TRUE;
      }
      else {
         usage();
         return -1;
      }
   }

   x_dpy = XOpenDisplay(dpyName);
   if (!x_dpy) {
      printf("Error: couldn't open display %s\n",
	     dpyName ? dpyName : getenv("DISPLAY"));
      return -1;
   }

   egl_dpy = eglGetDisplay(x_dpy);
   if (!egl_dpy) {
      printf("Error: eglGetDisplay() failed\n");
      return -1;
   }

   if (!eglInitialize(egl_dpy, &egl_major, &egl_minor)) {
      printf("Error: eglInitialize() failed\n");
      return -1;
   }

   s = eglQueryString(egl_dpy, EGL_VERSION);
   printf("EGL_VERSION = %s\n", s);

   s = eglQueryString(egl_dpy, EGL_VENDOR);
   printf("EGL_VENDOR = %s\n", s);

   s = eglQueryString(egl_dpy, EGL_EXTENSIONS);
   printf("EGL_EXTENSIONS = %s\n", s);

   s = eglQueryString(egl_dpy, EGL_CLIENT_APIS);
   printf("EGL_CLIENT_APIS = %s\n", s);

   make_x_window(x_dpy, egl_dpy,
                 "OpenGL ES 2.x tri", 0, 0, winWidth, winHeight,
                 &win, &egl_ctx, &egl_surf);

   XMapWindow(x_dpy, win);
   if (!eglMakeCurrent(egl_dpy, egl_surf, egl_surf, egl_ctx)) {
      printf("Error: eglMakeCurrent() failed\n");
      return -1;
   }

   if (printInfo) {
      printf("GL_RENDERER   = %s\n", (char *) glGetString(GL_RENDERER));
      printf("GL_VERSION    = %s\n", (char *) glGetString(GL_VERSION));
      printf("GL_VENDOR     = %s\n", (char *) glGetString(GL_VENDOR));
      printf("GL_EXTENSIONS = %s\n", (char *) glGetString(GL_EXTENSIONS));
   }

   init();

   /* Set initial projection/viewing transformation.
    * We can't be sure we'll get a ConfigureNotify event when the window
    * first appears.
    */
   reshape(winWidth, winHeight);

   event_loop(x_dpy, win, egl_dpy, egl_surf);

   eglDestroyContext(egl_dpy, egl_ctx);
   eglDestroySurface(egl_dpy, egl_surf);
   eglTerminate(egl_dpy);


   XDestroyWindow(x_dpy, win);
   XCloseDisplay(x_dpy);

   return 0;
}