#include "fish_painter.h"

#include "OBJ_Loader.h"
#include <QtMath>
#include <locale>
#include <QImage>


FishPainter::~FishPainter() {
	if (texture) delete texture;
}


void FishPainter::create(QOpenGLExtraFunctions *glf) {
	(void) glf;

	if (!program.addShaderFromSourceFile(QOpenGLShader::Vertex,
										 ":/shaders/fish.vert")) {
		qCritical() << program.log();
	}
	if (!program.addShaderFromSourceFile(QOpenGLShader::Fragment,
										 ":/shaders/fish.frag")) {
		qCritical() << program.log();
	}
	if (!program.link()) {
		qCritical() << program.log();
	}

	texture = new QOpenGLTexture(QImage(":/textures/fish.jpg").mirrored());

	vao.create();

	{QOpenGLVertexArrayObject::Binder bind(&vao);
		vbo.create();
		vbo.bind();
		std::locale old_locale = std::locale::global(std::locale::classic()); // lmao posix sucks so much
		objl::Loader loader;
		if (!loader.LoadFile(":/meshes/fish.obj")) {
			qCritical() << "Unable to load fish mesh.";
		}
		std::locale::global(old_locale);
		std::vector<objl::Vertex> verts = loader.LoadedMeshes[0].Vertices;
		n_verts = verts.size();
		vbo.allocate(verts.data(), verts.size() * sizeof (objl::Vertex));
		program.bind();
		program.setAttributeBuffer("position", GL_FLOAT,
								   offsetof(objl::Vertex, Position),
								   3, sizeof (objl::Vertex));
		program.setAttributeBuffer("uv", GL_FLOAT,
								   offsetof(objl::Vertex, TextureCoordinate),
								   2, sizeof (objl::Vertex));
		program.enableAttributeArray("position");
		program.enableAttributeArray("uv");
	}
}


void FishPainter::paint(QOpenGLExtraFunctions *glf,
						   const QMatrix4x4 &projection,
						   const QMatrix4x4 &view,
						   const std::vector<Fish> fishes) {
	const QVector3D X(1, 0, 0);
	{QOpenGLVertexArrayObject::Binder bind(&vao);
		program.setUniformValue("projection", projection);
		program.setUniformValue("view", view);
		texture->bind();
		QMatrix4x4 model;
		for (const Fish &fish : fishes) {
			model.setToIdentity();
			model.translate(fish.position);
			if (!fish.velocity.isNull()) {
				double dot = QVector3D::dotProduct(X, fish.velocity);
				double angle = qAcos(dot / fish.velocity.length());
				if (angle != 0) {
					model.rotate(qRadiansToDegrees(angle),
								 QVector3D::crossProduct(X, fish.velocity));
				}
			}
			program.setUniformValue("model", model);
			glf->glDrawArrays(GL_TRIANGLES, 0, n_verts);
		}
	}
}