#include "fish_painter.h"

#include <QtMath>


const GLfloat vertices[] = {
	1, 0, 0,
	-1, .5, 0,
	-1, -.5, 0,
};


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();
	}

	vao.create();

	{QOpenGLVertexArrayObject::Binder bind(&vao);
		vbo.create();
		vbo.bind();
		vbo.allocate(vertices, 9 * sizeof (GLfloat));
		program.bind();
		program.setAttributeBuffer("position", GL_FLOAT, 0, 3);
		program.enableAttributeArray("position");
	}
}


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);
		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, 3);
		}
	}
}