src/gl/compiler.cpp

/*
 *  LDForge: LDraw parts authoring CAD
 *  Copyright (C) 2013 - 2018 Teemu Piippo
 *
 *  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://www.gnu.org/licenses/>.
 */

#define GL_GLEXT_PROTOTYPES
#include <GL/glu.h>
#include <GL/glext.h>
#include "gl/compiler.h"
#include "documentmanager.h"
#include "invert.h"
#include "ring.h"

gl::Compiler::Compiler(QObject* parent) :
	QObject{parent}
{
}

gl::Compiler::~Compiler()
{

}

void gl::Compiler::build(Model* model, DocumentManager* context)
{
	if (not this->initialized)
	{
		this->initializeVbo();
	}
	std::vector<GLfloat> vboData[gl::numVbos];
	const std::vector<gl::Polygon> polygons = model->getPolygons(context);
	for (const gl::Polygon& polygon : polygons)
	{
		this->buildPolygon(polygon, vboData);
	}
	for (int i = 0; i < gl::numVbos; i += 1)
	{
		this->upload(i, vboData[i]);
	}
}

gl::VboClass classifyPolygon(const gl::Polygon& polygon)
{
	switch (polygon.type)
	{
	case gl::Polygon::EdgeLine:
		return gl::VboClass::Lines;
	case gl::Polygon::Triangle:
		return gl::VboClass::Triangles;
	case gl::Polygon::Quadrilateral:
		return gl::VboClass::Quads;
	case gl::Polygon::ConditionalEdge:
		return gl::VboClass::ConditionalLines;
	}
	return gl::VboClass::Lines;
}

QColor colorFromId(linetypes::Id id)
{
	// Calculate a color based from this index. This method caters for
	// 16777216 objects. I don't think that will be exceeded anytime soon.
	const int r = (id.value / 0x10000) % 0x100;
	const int g = (id.value / 0x100) % 0x100;
	const int b = id.value % 0x100;
	return {r, g, b};
}

void writeVertex(std::vector<GLfloat>& data, const Point3D& point)
{
	data.push_back(point.x);
	data.push_back(point.y);
	data.push_back(point.z);
}

void gl::Compiler::buildPolygon(gl::Polygon polygon, std::vector<GLfloat>* vboData)
{
	const gl::VboClass vboClass = classifyPolygon(polygon);
	auto vboBuffer = [&](VboSubclass subclass) -> std::vector<GLfloat>&
	{
		return vboData[gl::vboIndex({vboClass, subclass})];
	};
	auto vertexRing = iter::ring(polygon.vertices, polygon.numPolygonVertices());
	for (int i = 0; i < polygon.numPolygonVertices(); i += 1)
	{
		const Point3D& v1 = vertexRing[i - 1];
		const Point3D& v2 = vertexRing[i];
		const Point3D& v3 = vertexRing[i + 1];
		const QVector3D normal = QVector3D::crossProduct(v3 - v2, v1 - v2).normalized();
		std::vector<GLfloat>& data = vboBuffer(VboSubclass::Normals);
		for (const GLfloat coord : {normal.x(), normal.y(), normal.z()})
			data.push_back(coord);
	}
	vboBuffer(VboSubclass::Surfaces).reserve(vboBuffer(VboSubclass::Surfaces).size() + polygon.numPolygonVertices());
	// Transform vertices so that they're suitable for GL rendering
	for (int i = 0; i < polygon.numPolygonVertices(); i += 1)
	{
		polygon.vertices[i].y = -polygon.vertices[i].y;
		polygon.vertices[i].z = -polygon.vertices[i].z;
#if 0
		// Add these vertices to the bounding box (unless we're going to do it over
		// from scratch afterwards anyway)
		if (not this->needBoundingBoxRebuild)
		{
			this->boundingBox.consider(poly.vertices[i]);
		}
#endif
		writeVertex(vboBuffer(VboSubclass::Surfaces), polygon.vertices[i]);
	}
	this->writeColor(vboData, polygon, VboSubclass::RegularColors);
	this->writeColor(vboData, polygon, VboSubclass::PickColors);
	this->writeColor(vboData, polygon, VboSubclass::BfcFrontColors);
	this->writeColor(vboData, polygon, VboSubclass::BfcBackColors);
}

QColor gl::Compiler::getColorForPolygon(const gl::Polygon& polygon, VboSubclass subclass)
{
	QColor color;

	switch (subclass)
	{
	case VboSubclass::Surfaces:
	case VboSubclass::Normals:
	case VboSubclass::InvertedNormals:
		// Surface and normal VBOs contain vertex data, not colors. So we can't return anything meaningful.
		return {};
	case VboSubclass::BfcFrontColors:
		// Use the constant green color for BFC front colors
		return {64, 192, 80};
	case VboSubclass::BfcBackColors:
		// Use the constant red color for BFC back colors
		return {208, 64, 64};
	case VboSubclass::PickColors:
		// For the picking scene, use unique picking colors provided by the model.
		return colorFromId(polygon.id);
	case VboSubclass::RandomColors:
		// For the random color scene, the owner object has rolled up a random color. Use that.
		color = {255, 64, 255}; // polygonOwner->randomColor();
		break;
	case VboSubclass::RegularColors:
		// For normal colors, use the polygon's color.
		if (polygon.color == colors::main)
		{
			color = {255, 255, 64}; // mainColorRepresentation();
		}
		else if (polygon.color == colors::edge)
		{
			// Edge color is black, unless we have a dark background, in which case lines need to be bright.
			color = Qt::black; //luma(config::backgroundColor()) > 40 ? Qt::black : Qt::white;
		}
		else
		{
			// Not main or edge color, use the polygon's color as is.
			color = {255, 255, 64}; //polygon.color.faceColor();
		}
		break;
	}

	if (color.isValid())
	{
		// We may wish to apply blending on the color to indicate selection or highlight.
		/*
		const double blendAlpha = 0.0;
		if (blendAlpha != 0.0)
		{
			QColor selectedColor = config::selectColorBlend();
			double denominator = blendAlpha + 1.0;
			color.setRed((color.red() + (selectedColor.red() * blendAlpha)) / denominator);
			color.setGreen((color.green() + (selectedColor.green() * blendAlpha)) / denominator);
			color.setBlue((color.blue() + (selectedColor.blue() * blendAlpha)) / denominator);
		}
		*/
	}
	else
	{
		if (polygon.numPolygonVertices() == 2)
			color = Qt::black;
		else
			color = {255, 255, 64};
	}

	return color;
}

void gl::Compiler::writeColor(std::vector<GLfloat>* data, const gl::Polygon& polygon, VboSubclass subclass)
{
	std::vector<GLfloat>& buffer = data[gl::vboIndex({classifyPolygon(polygon), subclass})];
	const QColor color = this->getColorForPolygon(polygon, subclass);
	buffer.reserve(data->size() + 4 * polygon.numPolygonVertices());
	for (int i = 0; i < polygon.numPolygonVertices(); i += 1)
	{
		buffer.push_back(color.redF() / 255.0f);
		buffer.push_back(color.greenF() / 255.0f);
		buffer.push_back(color.blueF() / 255.0f);
		buffer.push_back(color.alphaF() / 255.0f);
	}
}

void gl::Compiler::initializeVbo()
{
	this->initializeOpenGLFunctions();
	glGenBuffers(countof(this->storedVbo), &this->storedVbo[0]);
	this->initialized = true;
}

///
/// \brief Uploads data to a vbo
/// \param vboAddress Which vbo to upload to
/// \param data Data to upload to vbo
///
void gl::Compiler::upload(const int vboIndex, const std::vector<GLfloat>& data)
{
	glBindBuffer(GL_ARRAY_BUFFER, this->storedVbo[vboIndex]);
	glBufferData(GL_ARRAY_BUFFER, data.size() * sizeof data[0], data.data(), GL_STATIC_DRAW);
	glBindBuffer(GL_ARRAY_BUFFER, 0);
	this->storedVboSizes[vboIndex] = data.size();
}

GLuint gl::Compiler::vbo(const VboAddress vboAddress) const
{
	return this->storedVbo[gl::vboIndex(vboAddress)];
}

int gl::Compiler::vboSize(const VboAddress vboAddress) const
{
	return this->storedVboSizes[gl::vboIndex(vboAddress)];
}

int gl::vboIndex(const VboAddress vboAddress)
{
	return static_cast<std::uint8_t>(vboAddress.vboClass) * gl::numVboSubclasses
		+ static_cast<std::uint8_t>(vboAddress.vboSubclass);
}