/*
   render/state.cc
   This file is part of the Osirion project and is distributed under
   the terms of the GNU General Public License version 2
*/

#include <string>
#include <sstream>

#include "SDL/SDL.h"

#include "render/state.h"
#include "render/gl.h"
#include "render/render.h"

namespace render
{

int	State::render_width = 0;
int 	State::render_height = 0;
float	State::render_aspect = 0;
bool	State::render_has_generate_mipmaps = false;
bool	State::render_has_vbo = false;
GLuint	State::render_vbo = 0;

void State::init(int width, int height)
{
	resize(width, height);

	render_has_generate_mipmaps = false;

	std::string version(gl::version());
	for (size_t i = 0; i < version.size(); i++) {
		if (version[i] == '.')
			version[i] = ' ';
	}

	std::stringstream versionstream(version);
	int major, minor;
	if (versionstream >> major >> minor) {

		if (major > 1) {
			render_has_generate_mipmaps = true;
		} else if (major == 1) {
			if (minor > 3)
				render_has_generate_mipmaps = true;
		}

	} else {
		con_warn << "Could not determine OpenGL version!" << std::endl;
	}
	
	con_print << "  hardware generated mipmaps ";
	if (render_has_generate_mipmaps)
		con_print << "available" << std::endl;
	else
		con_print << "not available" << std::endl;
	
	// initialize gl functions
	render_has_vbo = true;
	gl::genbuffers = (gl::genbuffers_func) SDL_GL_GetProcAddress("glGenBuffers");
	if (!gl::genbuffers) {
		con_debug << "  glGenBuffers not available" << std::endl;
		render_has_vbo = false;
	}
	
	gl::deletebuffers = (gl::deletebuffers_func) SDL_GL_GetProcAddress("glDeleteBuffers");
	if (!gl::deletebuffers) {
		con_debug << "  glDeleteBuffers not available" << std::endl;
		render_has_vbo = false;
	}

	gl::bindbuffer = (gl::bindbuffer_func) SDL_GL_GetProcAddress("glBindBuffer");
	if (!gl::bindbuffer) {
		con_debug << "  glBindBuffer not available" << std::endl;
		render_has_vbo = false;
	}
	
	gl::bufferdata = (gl::bufferdata_func) SDL_GL_GetProcAddress("glBufferData");
	if (!gl::bufferdata) {
		con_debug << "  glBufferData not available" << std::endl;
		render_has_vbo = false;
	}

	con_print << "  vertex bufer objects ";
	if (render_has_vbo)
		con_print << "enabled" << std::endl;
	else
		con_print << "disabled" << std::endl;

	// Generate VBO
	if (render_has_vbo)
		gl::genbuffers(1, &render_vbo);
}

void State::shutdown()
{
	// Delete VBO
	if (render_has_vbo)
		gl::deletebuffers(1, &render_vbo);
}

void State::resize(int width, int height)
{
	render_width = width;
	render_height = height;

	render_aspect = (float) width / (float) height;

	clear();
}

void State::clear()
{
	// set viewport
	gl::viewport(0, 0, render_width, render_height);

	// set clear color
	gl::clearcolor(0.0f, 0.0f, 0.0f, 1.0f);

	// load identity matrices
	gl::matrixmode(GL_PROJECTION);
	gl::loadidentity();

	gl::matrixmode(GL_MODELVIEW);
	gl::loadidentity();

	// shading model: Gouraud (smooth, the default)
	gl::shademodel(GL_SMOOTH);
	//gl::shademodel(GL_FLAT);

	// color tracking
	glColorMaterial(GL_FRONT, GL_AMBIENT_AND_DIFFUSE);

	// material settings
	GLfloat specular_reflectance[] = { 0.2f, 0.2f, 0.2f, 1.0f };
	glMaterialfv(GL_FRONT, GL_SPECULAR, specular_reflectance);
	glMateriali(GL_FRONT, GL_SHININESS, 128); // shininess 1-128

	// alpha blending function
	gl::blendfunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

	gl::disable(GL_LIGHTING);
	gl::disable(GL_COLOR_MATERIAL);

	gl::cullface(GL_BACK);
	gl::frontface(GL_CCW);
	gl::disable(GL_CULL_FACE);
	gl::disable(GL_DEPTH_TEST);
	gl::disable(GL_BLEND);

	gl::disable(GL_TEXTURE_2D);
}

void State::set_normalize(const bool enable)
{
	if (r_normalize && r_normalize->value()) {
		// enable full normalization
		if(enable) {
			gl::enable(GL_NORMALIZE);
		} else {
			gl::disable(GL_NORMALIZE);
		}
	} else {
		// enable rescaling of normals
		if(enable) {
			gl::enable(GL_RESCALE_NORMAL);
		} else {
			gl::disable(GL_RESCALE_NORMAL);
		}
	}
}

} // namespace render