src/gl/axesprogram.cpp

/*
 *  LDForge: LDraw parts authoring CAD
 *  Copyright (C) 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 "gridprogram.h"

// Based on https://stackoverflow.com/q/30842755
const char vertexShaderSource[] = R"(
#version 330 core

layout (location = 0) in vec3 in_position;
layout (location = 1) in vec3 in_color;
uniform mat4 view;
uniform mat4 projection;
uniform mat4 model;
smooth out vec3 ex_color;

void main()
{
	gl_Position = projection * view * model * vec4(in_position, 0.0, 1.0);
	ex_uv = ex_color;
}
)";

const char fragmentShaderSource[] = R"(
#version 330 core

out vec4 color;
smooth in vec3 ex_color;

void main(void)
{
	color = vec4(ex_color, 1)
}
)";

namespace
{
	struct AxesVertex
	{
		glm::vec3 position;
		glm::vec3 color;
	};
}

static AxesVertex data[] =
{
	AxesVertex{{-10000, 0, 0}, {1, 0, 0}},
	AxesVertex{{10000, 0, 0}, {1, 0, 0}},
	AxesVertex{{0, -10000, 0}, {0, 1, 0}},
	AxesVertex{{0, 10000, 0}, {0, 1, 0}},
	AxesVertex{{0, 0, -10000}, {0, 0, 1}},
	AxesVertex{{0, 0, 10000}, {0, 0, 1}},
};

AxesProgram::AxesProgram(QObject* parent) :
	QObject{parent},
	buffer{QOpenGLBuffer::VertexBuffer},
	vertexShader{QOpenGLShader::Vertex},
	fragmentShader{QOpenGLShader::Fragment}
{
}

void AxesProgram::initialize()
{
	if (not isInitialized)
	{
		this->initializeOpenGLFunctions();
		this->isInitialized = true;
		this->program.emplace(this);
		gl::buildShaders(&*this->program, ::vertexShaderSource, ::fragmentShaderSource);
		this->program->bind();
		this->buffer.create();
		this->buffer.bind();
		this->buffer.setUsagePattern(QOpenGLBuffer::StaticDraw);
		this->buffer.allocate(data, countof(data) * sizeof data[0]);
		this->vertexArrayObject.create();
		this->vertexArrayObject.bind();
		this->program->enableAttributeArray(0);
		this->program->setAttributeBuffer(0, GL_FLOAT, 0, 2, 0);
		this->program->setUniformVector("gridColor", this->gridColor);
		this->vertexArrayObject.release();
		this->buffer.release();
		this->program->release();
		this->checkForGLErrors();
	}
}

void AxesProgram::setViewMatrix(const glm::mat4& newViewMatrix)
{
	this->setMatrix("view", newViewMatrix);
}

void AxesProgram::setProjectionMatrix(const glm::mat4& newProjectionMatrix)
{
	this->setMatrix("projection", newProjectionMatrix);
}

void AxesProgram::setModelMatrix(const glm::mat4& newModelMatrix)
{
	this->setMatrix("model", newModelMatrix);
}

void AxesProgram::setGridMatrix(const glm::mat4& newGridMatrix)
{
	this->setMatrix("grid", newGridMatrix);
}

void AxesProgram::setMatrix(const char* name, const glm::mat4& matrix)
{
	Q_ASSERT(this->isInitialized);
	this->program->bind();
	this->program->setUniformMatrix(name, matrix);
	this->program->release();
	this->checkForGLErrors();
}

void GridProgram::setGridColor(const QColor& newGridColor)
{
	const glm::vec4 vec = gl::colorToVector4(newGridColor);
	if (this->isInitialized)
	{
		this->program->bind();
		this->program->setUniformVector("gridColor", vec);
		this->program->release();
		this->checkForGLErrors();
	}
	else
	{
		this->gridColor = vec;
	}
}

void GridProgram::draw()
{
	this->program->bind();
	this->vertexArrayObject.bind();
	glDrawArrays(GL_QUADS, 0, countof(data));
	this->vertexArrayObject.release();
	this->program->release();
	this->checkForGLErrors();
}

void GridProgram::teardown()
{
	this->vertexArrayObject.destroy();
	this->buffer.destroy();
	this->program.reset();
}

void GridProgram::checkForGLErrors()
{
	gl::checkForGLErrors(qobject_cast<QWidget*>(this->parent()));
}