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 "axesprogram.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, 1.0);
	ex_color = in_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}},
};

const char* AxesProgram::vertexShaderSource() const
{
	return ::vertexShaderSource;
}

const char* AxesProgram::fragmentShaderSource() const
{
	return ::fragmentShaderSource;
}

const void* AxesProgram::vertexData() const
{
	return ::data;
}

GLenum AxesProgram::drawMode() const
{
	return GL_LINES;
}

int AxesProgram::vertexSize() const
{
	return sizeof data[0];
}

int AxesProgram::vertexCount() const
{
	return countof(data);
}

void AxesProgram::setupVertexArrays()
{
	for (int i : {0, 1})
	{
		this->program->enableAttributeArray(i);
	}
	const int stride = this->vertexSize();
	this->program->setAttributeBuffer(0, GL_FLOAT, offsetof(AxesVertex, position), 3, stride);
	this->program->setAttributeBuffer(1, GL_FLOAT, offsetof(AxesVertex, color), 3, stride);
}