/*

    ......... 2015 Ivan Mahonin

    This program is free software: you can redistribute it and/or modify

    it under the terms of the GNU General Public License as published by

    the Free Software Foundation, either version 3 of the License, or

    (at your option) any later version.

    This program is distributed in the hope that it will be useful,

    but WITHOUT ANY WARRANTY; without even the implied warranty of

    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License

    along with this program.  If not, see <http: licenses="" www.gnu.org="">.</http:>

*/

#include <cassert></cassert>

#include <iostream></iostream>

#include <iomanip></iomanip>

#include "glcontext.h"

using namespace std;

#define GLX_CONTEXT_MAJOR_VERSION_ARB 0x2091

#define GLX_CONTEXT_MINOR_VERSION_ARB 0x2092

typedef GLXContext (*GLXCREATECONTEXTATTRIBSARBPROC)(Display*, GLXFBConfig, GLXContext, Bool, const int*);

GlContext::GlContext():

	display(),

	pbuffer(),

	context(),

	texture_id(),

	framebuffer_id(),

	renderbuffer_id(),

	multisample_texture_id(),

	multisample_renderbuffer_id(),

	multisample_framebuffer_id()

{

	// options

	int framebuffer_width = 512;

	int framebuffer_height = 512;

	int framebuffer_samples = 16;

	bool antialising = false;

	bool hdr = true;

	// display

	display = XOpenDisplay(NULL);

	assert(display);

	// config

	int config_attribs[] = {

		GLX_DOUBLEBUFFER,      False,

		GLX_RED_SIZE,          8,

		GLX_GREEN_SIZE,        8,

		GLX_BLUE_SIZE,         8,

		GLX_ALPHA_SIZE,        8,

		GLX_DEPTH_SIZE,        24,

		GLX_STENCIL_SIZE,      8,

		GLX_ACCUM_RED_SIZE,    8,

		GLX_ACCUM_GREEN_SIZE,  8,

		GLX_ACCUM_BLUE_SIZE,   8,

		GLX_ACCUM_ALPHA_SIZE,  8,

		GLX_DRAWABLE_TYPE,     GLX_PBUFFER_BIT,

		None };

	int nelements = 0;

	GLXFBConfig *configs = glXChooseFBConfig(display, 0, config_attribs, &nelements);

	assert(configs != NULL && nelements > 0);

	GLXFBConfig config = configs[0];

	assert(config);

	// pbuffer

	int pbuffer_attribs[] = {

		GLX_PBUFFER_WIDTH, 256,

		GLX_PBUFFER_HEIGHT, 256,

		None };

	pbuffer = glXCreatePbuffer(display, config, pbuffer_attribs);

	assert(pbuffer);

	// context

	int context_attribs[] = {

		GLX_CONTEXT_MAJOR_VERSION_ARB, 3,

		GLX_CONTEXT_MINOR_VERSION_ARB, 3,

		None };

	GLXCREATECONTEXTATTRIBSARBPROC glXCreateContextAttribsARB = (GLXCREATECONTEXTATTRIBSARBPROC) glXGetProcAddress((const GLubyte*)"glXCreateContextAttribsARB");

	context = glXCreateContextAttribsARB(display, config, NULL, True, context_attribs);

	assert(context);

	glXMakeContextCurrent(display, pbuffer, pbuffer, context);

	// frame buffer

	GLenum internal_format = hdr ? GL_RGBA16F : GL_RGBA;

	GLenum color_type = hdr ? GL_FLOAT : GL_UNSIGNED_BYTE;

	glGenTextures(1, &texture_id);

	glBindTexture(GL_TEXTURE_2D, texture_id);

	glTexImage2D(GL_TEXTURE_2D, 0, internal_format, framebuffer_width, framebuffer_height, 0, GL_RGBA, color_type, NULL);

	glGenRenderbuffers(1, &renderbuffer_id);

	glBindRenderbuffer(GL_RENDERBUFFER, renderbuffer_id);

	glRenderbufferStorage(GL_RENDERBUFFER, GL_STENCIL_INDEX8, framebuffer_width, framebuffer_height);

	glGenFramebuffers(1, &framebuffer_id);

	glBindFramebuffer(GL_READ_FRAMEBUFFER, framebuffer_id);

	glFramebufferRenderbuffer(GL_READ_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_RENDERBUFFER, renderbuffer_id);

	glFramebufferTexture2D(GL_READ_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texture_id, 0);

	glGenTextures(1, &multisample_texture_id);

	glBindTexture(GL_TEXTURE_2D_MULTISAMPLE, multisample_texture_id);

	glTexImage2DMultisample(GL_TEXTURE_2D_MULTISAMPLE, framebuffer_samples, internal_format, framebuffer_width, framebuffer_height, GL_TRUE);

	glGenRenderbuffers(1, &multisample_renderbuffer_id);

	glBindRenderbuffer(GL_RENDERBUFFER, multisample_renderbuffer_id);

	glRenderbufferStorageMultisample(GL_RENDERBUFFER, framebuffer_samples, GL_STENCIL_INDEX8, framebuffer_width, framebuffer_height);

	glGenFramebuffers(1, &multisample_framebuffer_id);

	glBindFramebuffer(GL_DRAW_FRAMEBUFFER, multisample_framebuffer_id);

	glFramebufferRenderbuffer(GL_DRAW_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_RENDERBUFFER, multisample_renderbuffer_id);

	glFramebufferTexture2D(GL_DRAW_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D_MULTISAMPLE, multisample_texture_id, 0);

	cout << "Framebuffer status:" << setbase(16)

		 << " 0x" << glCheckFramebufferStatus(GL_DRAW_FRAMEBUFFER)

		 << " 0x" << glCheckFramebufferStatus(GL_READ_FRAMEBUFFER)

		 << setbase(10) << endl;

	if (antialising)

		glEnable(GL_MULTISAMPLE);

	else

		glBindFramebuffer(GL_DRAW_FRAMEBUFFER, framebuffer_id);

	// view port

	glViewport(0, 0, framebuffer_width, framebuffer_height);

	check();

}

GlContext::~GlContext() {

	glBindFramebuffer(GL_READ_FRAMEBUFFER, 0);

	glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);

	glBindTexture(GL_TEXTURE_2D, 0);

	glBindTexture(GL_TEXTURE_2D_MULTISAMPLE, 0);

	glBindRenderbuffer(GL_RENDERBUFFER, 0);

	glDeleteFramebuffers(1, &framebuffer_id);

	glDeleteRenderbuffers(1, &renderbuffer_id);

	glDeleteTextures(1, &texture_id);

	glDeleteFramebuffers(1, &multisample_framebuffer_id);

	glDeleteRenderbuffers(1, &multisample_renderbuffer_id);

	glDeleteTextures(1, &multisample_texture_id);

	glXMakeContextCurrent(display, None, None, NULL);

	glXDestroyContext(display, context);

	glXDestroyPbuffer(display, pbuffer);

	XCloseDisplay(display);

}

void GlContext::check(const std::string &s) {

	if (GLenum error = glGetError())

		cout << s << " GL error: 0x" << setbase(16) << error << setbase(10) << endl;

}