box.cpp

#include "box.h"

#include <QVector2D>
#include <QVector3D>

Box :: Box(float w, float h, float l)
: width (w)
, height (h)
, length (l)
{
	initializeOpenGLFunctions();
	initGeometry();
}

void Box::initGeometry()
{
	float hw = width / 2, hh = height / 2, hl = length / 2;
	// For cube we would need only 8 vertices but we have to
	// duplicate vertex for each face because texture coordinate
	// is different.
	VertexData vertices [] = {
	// Vertex data for face 0
    {QVector3D(-hw, -hh,  hl), QVector2D(.0f, .0f)},  // v0
    {QVector3D( hw, -hh,  hl), QVector2D(.33f, .0f)}, // v1
    {QVector3D(-hw,  hh,  hl), QVector2D(.0f, .5f)},  // v2
    {QVector3D( hw,  hh,  hl), QVector2D(.33f, .5f)}, // v3

	// Vertex data for face 1
    {QVector3D( hw, -hh,  hl), QVector2D(.0f, .5f)}, // v4
    {QVector3D( hw, -hh, -hl), QVector2D(.33f, .5f)}, // v5
    {QVector3D( hw,  hh,  hl), QVector2D(.0f, 1.0f)},  // v6
    {QVector3D( hw,  hh, -hl), QVector2D(.33f, 1.0f)}, // v7

	// Vertex data for face 2
    {QVector3D( hw, -hh, -hl), QVector2D(.66f, .5f)}, // v8
    {QVector3D(-hw, -hh, -hl), QVector2D(1.0f, .5f)},  // v9
    {QVector3D( hw,  hh, -hl), QVector2D(.66f, 1.0f)}, // v10
    {QVector3D(-hw,  hh, -hl), QVector2D(1.0f, 1.0f)},  // v11

	// Vertex data for face 3
    {QVector3D(-hw, -hh, -hl), QVector2D(.66f, .0f)}, // v12
    {QVector3D(-hw, -hh,  hl), QVector2D(1.0f, .0f)},  // v13
    {QVector3D(-hw,  hh, -hl), QVector2D(.66f, .5f)}, // v14
    {QVector3D(-hw,  hh,  hl), QVector2D(1.0f, .5f)},  // v15

	// Vertex data for face 4
    {QVector3D(-hw, -hh, -hl), QVector2D(.33f, .0f)}, // v16
    {QVector3D( hw, -hh, -hl), QVector2D(.66f, .0f)}, // v17
    {QVector3D(-hw, -hh,  hl), QVector2D(.33f, .5f)}, // v18
    {QVector3D( hw, -hh,  hl), QVector2D(.66f, .5f)}, // v19

	// Vertex data for face 5
    {QVector3D(-hw,  hh,  hl), QVector2D(.33f, .5f)}, // v20
    {QVector3D( hw,  hh,  hl), QVector2D(.66f, .5f)}, // v21
    {QVector3D(-hw,  hh, -hl), QVector2D(.33f, 1.0f)}, // v22
    {QVector3D( hw,  hh, -hl), QVector2D(.66f, 1.0f)}  // v23
	};

	// Indices for drawing cube faces using triangle strips.
	// Triangle strips can be connected by duplicating indices
	// between the strips. If connecting strips have opposite
	// vertex order then last index of the first strip and first
	// index of the second strip needs to be duplicated. If
	// connecting strips have same vertex order then only last
	// index of the first strip needs to be duplicated.
	Geometry::indicetype_t indices [] = {
        0,  1,  2,  3,  3     // Face 0 - triangle strip ( v0,  v1,  v2,  v3)
        , 4,  4,  5,  6,  7,  7 // Face 1 - triangle strip ( v4,  v5,  v6,  v7)
        , 8,  8,  9, 10, 11, 11 // Face 2 - triangle strip ( v8,  v9, v10, v11)
        , 12, 12, 13, 14, 15, 15 // Face 3 - triangle strip (v12, v13, v14, v15)
        ,  16, 16, 17, 18, 19, 19 // Face 4 - triangle strip (v16, v17, v18, v19)
        , 20, 20, 21, 22, 23      // Face 5 - triangle strip (v20, v21, v22, v23)
	};

	// Transfer vertex data to VBO 0
    geometry.vertices.bind ();
    geometry.vertices.allocate (vertices , sizeof (vertices));

	// Transfer index data to VBO 1
    geometry.indices.bind ();
//    geometry.indices.allocate (indices, sizeof (indices) * 2);
    geometry.indices.allocate (indices, sizeof (indices));
}