src/gl/partrenderer.cpp

/*
 *  LDForge: LDraw parts authoring CAD
 *  Copyright (C) 2013 - 2020 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/>.
 */

#include <GL/glut.h>
#include <QMouseEvent>
#include <QMessageBox>
#include "partrenderer.h"

PartRenderer::PartRenderer(Model* model, DocumentManager* documents, const ColorTable& colorTable, QWidget* parent) :
	QOpenGLWidget{parent},
	model{model},
	documents{documents},
	colorTable{colorTable},
	compiler{new gl::Compiler{this->colorTable, this}}
{
	this->setMouseTracking(true);
}

PartRenderer::~PartRenderer()
{
}

void PartRenderer::initializeGL()
{
	this->initializeOpenGLFunctions();
	if (glGetError() != GL_NO_ERROR)
	{
		abort();
	}
	glEnableClientState(GL_NORMAL_ARRAY);
	glEnableClientState(GL_VERTEX_ARRAY);
	this->compiler->initialize();
	this->compiler->build(this->model, this->documents);
	this->initializeLighting();
	this->initialized = true;
	this->rotation = QQuaternion::fromAxisAndAngle({1, 0, 0}, 30);
	this->rotation *= QQuaternion::fromAxisAndAngle({0, 1, 0}, 330);
	glLineWidth(2.0);
}

/*
 * Pads a 3×3 matrix into a 4×4 one by adding cells from the identity matrix.
 */
static QMatrix4x4 padMatrix(const QMatrix3x3& stub)
{
	return {
		stub(0, 0), stub(0, 1), stub(0, 2), 0,
		stub(1, 0), stub(1, 1), stub(1, 2), 0,
		stub(2, 0), stub(2, 1), stub(2, 2), 0,
		0, 0, 0, 1
	};
}


void PartRenderer::initializeLighting()
{
	GLfloat materialShininess[] = {5.0};
	GLfloat lightPosition[] = {1.0, 1.0, 1.0, 0.0};
	GLfloat ambientLightingLevel[] = {0.5, 0.5, 0.5, 1.0};
	glShadeModel(GL_SMOOTH);
	glMaterialfv(GL_FRONT, GL_SHININESS, materialShininess);
	glLightfv(GL_LIGHT0, GL_AMBIENT, ambientLightingLevel);
	glLightfv(GL_LIGHT0, GL_DIFFUSE, ambientLightingLevel);
	glLightfv(GL_LIGHT0, GL_POSITION, lightPosition);
	glEnable(GL_LIGHTING);
	glEnable(GL_LIGHT0);
	glEnable(GL_COLOR_MATERIAL);
	glEnable(GL_DEPTH_TEST);
}

void PartRenderer::resizeGL(int width, int height)
{
	constexpr GLdouble near = 1.0;
	constexpr GLdouble far = 1e+05;
	glViewport (0, 0, width, height);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	gluPerspective(45.0, static_cast<double>(width) / static_cast<double>(height), near, far);
	glMatrixMode(GL_MODELVIEW);
}

static GLenum getGlTypeForArrayClass(const gl::ArrayClass vboClass)
{
	switch (vboClass)
	{
	case gl::ArrayClass::Lines:
	case gl::ArrayClass::ConditionalLines:
		return GL_LINES;
	case gl::ArrayClass::Triangles:
		return GL_TRIANGLES;
	case gl::ArrayClass::Quads:
		return GL_QUADS;
	}
	throw std::runtime_error{"Bad vbo class passed to getGlTypeForVboClass"};
}

void PartRenderer::paintGL()
{
	/*
	glEnable (GL_BLEND);
	glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
	*/
	glEnable (GL_DEPTH_TEST);
	glShadeModel (GL_SMOOTH);
	glEnable (GL_MULTISAMPLE);
	glEnable (GL_LINE_SMOOTH);
	glHint (GL_LINE_SMOOTH_HINT, GL_NICEST);
	this->renderScene();
}

void PartRenderer::renderScene()
{
	glClearColor(0.8f, 0.8f, 0.8f, 1.0f);
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	glMatrixMode(GL_MODELVIEW);
	glEnable(GL_DEPTH_TEST);
	glEnable(GL_LIGHTING);
	glLoadIdentity();
	//glTranslated(0.0, 0.0, -4.5 * this->compiler->modelDistance());
	//glTranslated(0.0, 0.0, -4.5);
	//glMultMatrixf(padMatrix(this->rotation.toRotationMatrix()).constData());
	//xyz(glTranslatef, -this->compiler->modelCenter());
	auto rotationMatrix = padMatrix(this->rotation.toRotationMatrix());
	rotationMatrix(2, 3) = 0;
	glEnable(GL_POLYGON_OFFSET_FILL);
	glPolygonOffset(1.0f, 1.0f);
	switch (this->renderStyle)
	{
	case gl::RenderStyle::Normal:
	case gl::RenderStyle::BfcRedGreen:
	case gl::RenderStyle::RandomColors:
		break;
	case gl::RenderStyle::Wireframe:
		glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
		break;
	}
	this->compiler->setUniform("CameraTransformation", rotationMatrix);
	// Lines need to be rendered last so that anti-aliasing does not interfere with polygon rendering.
	renderVao(gl::ArrayClass::Triangles);
	renderVao(gl::ArrayClass::Quads);
	renderVao(gl::ArrayClass::Lines);
	glDisable(GL_POLYGON_OFFSET_FILL);
}

void PartRenderer::renderVao(const gl::ArrayClass arrayClass)
{
	this->compiler->bindVertexArray(arrayClass);
	const std::size_t vertexCount = this->compiler->vboSize(arrayClass) / gl::FLOATS_PER_VERTEX;
	glDrawArrays(getGlTypeForArrayClass(arrayClass), 0, static_cast<GLsizei>(vertexCount));
	this->compiler->releaseVertexArray(arrayClass);
	this->checkForGLErrors();
}

void PartRenderer::checkForGLErrors()
{
	GLenum glError;
	QStringList errors;
	while ((glError = glGetError()) != GL_NO_ERROR)
	{
		const QString glErrorString = QString::fromLatin1(reinterpret_cast<const char*>(::gluErrorString(glError)));
		errors.append(glErrorString);
	}
	if (not errors.isEmpty())
	{
		QMessageBox::critical(
			this,
			tr("Rendering error"),
			QString{"Failed to render.\n%1"}.arg(errors.join("\n")));
	}
}

void PartRenderer::mouseMoveEvent(QMouseEvent* event)
{
	const bool left = event->buttons() & Qt::LeftButton;
	const QPointF move = pointToPointF(event->pos()) - this->lastMousePosition;
	if (left and not move.isNull())
	{
		const QQuaternion versor = QQuaternion::fromAxisAndAngle(
			QVector3D{static_cast<float>(move.y()), static_cast<float>(move.x()), 0.0f},
			0.6f * static_cast<float>(std::hypot(move.x(), move.y()))
		);
		this->rotation = versor * this->rotation;
		this->update();
	}
	this->lastMousePosition = pointToPointF(event->pos());
}

void PartRenderer::setCompiler(gl::Compiler* compiler)
{
	this->compiler = compiler;
}

void PartRenderer::setRenderStyle(const gl::RenderStyle newStyle)
{
	this->renderStyle = newStyle;
	this->update();
}