#include "mesh_view.h"
#include <QOpenGLFunctions_2_1>


MeshView::MeshView(QOpenGLExtraFunctions *glf, const MyMesh &mesh,
				   int pos_attr, int col_attr)
	: glf(glf),
	  mesh(mesh) {
    GLfloat *verts = new GLfloat[mesh.n_faces() * 3 * 6];
	size_t i = 0;

	for (const FaceHandle face : mesh.faces()) {
		for (const VertexHandle vec : mesh.fv_range(face)) {
			verts[6*i + 0] = mesh.point(vec)[0];
			verts[6*i + 1] = mesh.point(vec)[1];
			verts[6*i + 2] = mesh.point(vec)[2];
			verts[6*i + 3] = mesh.color.red();
			verts[6*i + 4] = mesh.color.green();
			verts[6*i + 5] = mesh.color.blue();
			i++;
		}
    }

    delete[] verts;

	GLuint vao, vbo;
    glf->glGenVertexArrays(1, &vao);
	glf->glGenBuffers(1, &vbo);

    glf->glBindVertexArray(vao);
	glf->glBindBuffer(GL_ARRAY_BUFFER, vbo);
	glf->glBufferData(GL_ARRAY_BUFFER, nverts * 6 * sizeof (GLfloat), verts, GL_DYNAMIC_DRAW);
	glf->glVertexAttribPointer(pos_attr, 3, GL_FLOAT, GL_FALSE, 6 * sizeof (GLfloat), 0);
	glf->glEnableVertexAttribArray(pos_attr);
	glf->glVertexAttribPointer(col_attr, 3, GL_FLOAT, GL_FALSE, 6 * sizeof (GLfloat),
						  (const void *) (3 * sizeof (GLfloat)));
	glf->glEnableVertexAttribArray(col_attr);

	glf->glBindVertexArray(0);
}


MeshView::~MeshView() {
	glf->glDeleteVertexArrays(1, &vao);
	glf->glDeleteBuffers(1, &vbo);
}


void MeshView::paint(QOpenGLContext *ctx,
					 int model_attr, int wireframe_attr) const {
	void (*glPolygonMode)(GLenum, GLenum) = nullptr;
	glPolygonMode = (typeof glPolygonMode) ctx->getProcAddress("glPolygonMode");
	if (!glPolygonMode)
		qWarning("glPolygonMode not available");

	glf->glUniformMatrix4fv(model_attr, 1, GL_FALSE,
							mesh.transform.constData());

	/* Mesh */
	glf->glBindVertexArray(vao);
	glf->glEnable(GL_POLYGON_OFFSET_FILL);
	glf->glPolygonOffset(1.0, 2);
	glf->glDrawArrays(GL_TRIANGLES, 0, nverts);
	if (glPolygonMode) glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
	glf->glDisable(GL_POLYGON_OFFSET_FILL);

	/* Wireframe */
	glf->glUniform1f(wireframe_attr, 1);
	glf->glDrawArrays(GL_TRIANGLES, 0, nverts);
	if (glPolygonMode) glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
	glf->glLineWidth(3);
	glf->glUniform1f(wireframe_attr, 0);
}