/* ResidualVM - A 3D game interpreter
 *
 * ResidualVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the AUTHORS
 * file distributed with this source distribution.
 *
 * 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 2
 * 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, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 */

#include "engines/stark/gfx/openglsprop.h"

#include "engines/stark/scene.h"
#include "engines/stark/services/services.h"
#include "engines/stark/gfx/driver.h"
#include "engines/stark/gfx/texture.h"

#include "graphics/opengl/shader.h"

namespace Stark {
namespace Gfx {

OpenGLSPropRenderer::OpenGLSPropRenderer(Driver *gfx) :
		VisualProp(),
		_gfx(gfx),
		_faceVBO(-1) {
	static const char* attributes[] = { "position", "normal", "texcoord", nullptr };
	_shader = OpenGL::Shader::fromFiles("stark_prop", attributes);
}

OpenGLSPropRenderer::~OpenGLSPropRenderer() {
	clearVertices();

	delete _shader;
}

void OpenGLSPropRenderer::render(const Math::Vector3d position, float direction) {
	if (_faceVBO == -1) {
		// Update the OpenGL Buffer Objects if required
		clearVertices();
		uploadVertices();
	}

	_gfx->set3DMode();

	Math::Matrix4 model = getModelMatrix(position, direction);
	Math::Matrix4 view = StarkScene->getViewMatrix();
	Math::Matrix4 projection = StarkScene->getProjectionMatrix();

	Math::Matrix4 mvp = projection * view * model;
	mvp.transpose();

	_shader->use(true);
	_shader->setUniform("mvp", mvp);

	const Common::Array<Formats::BiffMesh::Face> &faces = _model->getFaces();
	const Common::Array<Formats::BiffMesh::Material> &materials = _model->getMaterials();

	for (Common::Array<Formats::BiffMesh::Face>::const_iterator face = faces.begin(); face != faces.end(); ++face) {
		const Formats::BiffMesh::Material &material = materials[face->materialId];

		// For each face draw its vertices from the VBO, indexed by the EBO
		const Gfx::Texture *tex = _texture->getTexture(material.texture);
		if (tex) {
			tex->bind();
		} else {
			glBindTexture(GL_TEXTURE_2D, 0);
		}

		GLuint ebo = _faceEBO[face];

		_shader->enableVertexAttribute("position", _faceVBO, 3, GL_FLOAT, GL_FALSE, 9 * sizeof(float), 0);
		_shader->enableVertexAttribute("normal", _faceVBO, 3, GL_FLOAT, GL_FALSE, 9 * sizeof(float), 12);
		_shader->enableVertexAttribute("texcoord", _faceVBO, 3, GL_FLOAT, GL_FALSE, 9 * sizeof(float), 24);
		_shader->use(true);
		_shader->setUniform("textured", tex != nullptr);
		_shader->setUniform("color", Math::Vector3d(material.r, material.g, material.b));

		glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo);
		glDrawElements(GL_TRIANGLES, face->vertexIndices.size(), GL_UNSIGNED_INT, 0);

		glUseProgram(0);
	}
}

void OpenGLSPropRenderer::clearVertices() {
	OpenGL::Shader::freeBuffer(_faceVBO);
	_faceVBO = -1;

	for (FaceBufferMap::iterator it = _faceEBO.begin(); it != _faceEBO.end(); ++it) {
		OpenGL::Shader::freeBuffer(it->_value);
	}

	_faceEBO.clear();
}

void OpenGLSPropRenderer::uploadVertices() {
	_faceVBO = createFaceVBO();

	const Common::Array<Formats::BiffMesh::Face> &faces = _model->getFaces();
	for (Common::Array<Formats::BiffMesh::Face>::const_iterator face = faces.begin(); face != faces.end(); ++face) {
		_faceEBO[face] = createFaceEBO(face);
	}
}

uint32 OpenGLSPropRenderer::createFaceVBO() {
	const Common::Array<Formats::BiffMesh::Vertex> &vertices = _model->getVertices();

	return OpenGL::Shader::createBuffer(GL_ARRAY_BUFFER, sizeof(float) * 9 * vertices.size(), &vertices.front());
}

uint32 OpenGLSPropRenderer::createFaceEBO(const Formats::BiffMesh::Face *face) {
	return OpenGL::Shader::createBuffer(GL_ELEMENT_ARRAY_BUFFER, sizeof(uint32) * face->vertexIndices.size(), &face->vertexIndices.front());
}

} // End of namespace Gfx
} // End of namespace Stark