qt5base-lts/examples/opengl/cube/geometryengine.cpp
Jani Heikkinen cd46a2daf5 Unify license header usage.
Update files using old header.LGPL3 to header.LGPL
Update files using old FDL template to use new one
Update files using old BSD template to use new one

Change-Id: I36a78272516f9953d02956522f285b40adfc8915
Reviewed-by: Lars Knoll <lars.knoll@theqtcompany.com>
2016-03-29 10:20:03 +00:00

180 lines
7.2 KiB
C++

/****************************************************************************
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** Copyright (C) 2016 The Qt Company Ltd.
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#include "geometryengine.h"
#include <QVector2D>
#include <QVector3D>
struct VertexData
{
QVector3D position;
QVector2D texCoord;
};
//! [0]
GeometryEngine::GeometryEngine()
: indexBuf(QOpenGLBuffer::IndexBuffer)
{
initializeOpenGLFunctions();
// Generate 2 VBOs
arrayBuf.create();
indexBuf.create();
// Initializes cube geometry and transfers it to VBOs
initCubeGeometry();
}
GeometryEngine::~GeometryEngine()
{
arrayBuf.destroy();
indexBuf.destroy();
}
//! [0]
void GeometryEngine::initCubeGeometry()
{
// 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(-1.0f, -1.0f, 1.0f), QVector2D(0.0f, 0.0f)}, // v0
{QVector3D( 1.0f, -1.0f, 1.0f), QVector2D(0.33f, 0.0f)}, // v1
{QVector3D(-1.0f, 1.0f, 1.0f), QVector2D(0.0f, 0.5f)}, // v2
{QVector3D( 1.0f, 1.0f, 1.0f), QVector2D(0.33f, 0.5f)}, // v3
// Vertex data for face 1
{QVector3D( 1.0f, -1.0f, 1.0f), QVector2D( 0.0f, 0.5f)}, // v4
{QVector3D( 1.0f, -1.0f, -1.0f), QVector2D(0.33f, 0.5f)}, // v5
{QVector3D( 1.0f, 1.0f, 1.0f), QVector2D(0.0f, 1.0f)}, // v6
{QVector3D( 1.0f, 1.0f, -1.0f), QVector2D(0.33f, 1.0f)}, // v7
// Vertex data for face 2
{QVector3D( 1.0f, -1.0f, -1.0f), QVector2D(0.66f, 0.5f)}, // v8
{QVector3D(-1.0f, -1.0f, -1.0f), QVector2D(1.0f, 0.5f)}, // v9
{QVector3D( 1.0f, 1.0f, -1.0f), QVector2D(0.66f, 1.0f)}, // v10
{QVector3D(-1.0f, 1.0f, -1.0f), QVector2D(1.0f, 1.0f)}, // v11
// Vertex data for face 3
{QVector3D(-1.0f, -1.0f, -1.0f), QVector2D(0.66f, 0.0f)}, // v12
{QVector3D(-1.0f, -1.0f, 1.0f), QVector2D(1.0f, 0.0f)}, // v13
{QVector3D(-1.0f, 1.0f, -1.0f), QVector2D(0.66f, 0.5f)}, // v14
{QVector3D(-1.0f, 1.0f, 1.0f), QVector2D(1.0f, 0.5f)}, // v15
// Vertex data for face 4
{QVector3D(-1.0f, -1.0f, -1.0f), QVector2D(0.33f, 0.0f)}, // v16
{QVector3D( 1.0f, -1.0f, -1.0f), QVector2D(0.66f, 0.0f)}, // v17
{QVector3D(-1.0f, -1.0f, 1.0f), QVector2D(0.33f, 0.5f)}, // v18
{QVector3D( 1.0f, -1.0f, 1.0f), QVector2D(0.66f, 0.5f)}, // v19
// Vertex data for face 5
{QVector3D(-1.0f, 1.0f, 1.0f), QVector2D(0.33f, 0.5f)}, // v20
{QVector3D( 1.0f, 1.0f, 1.0f), QVector2D(0.66f, 0.5f)}, // v21
{QVector3D(-1.0f, 1.0f, -1.0f), QVector2D(0.33f, 1.0f)}, // v22
{QVector3D( 1.0f, 1.0f, -1.0f), QVector2D(0.66f, 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.
GLushort 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)
};
//! [1]
// Transfer vertex data to VBO 0
arrayBuf.bind();
arrayBuf.allocate(vertices, 24 * sizeof(VertexData));
// Transfer index data to VBO 1
indexBuf.bind();
indexBuf.allocate(indices, 34 * sizeof(GLushort));
//! [1]
}
//! [2]
void GeometryEngine::drawCubeGeometry(QOpenGLShaderProgram *program)
{
// Tell OpenGL which VBOs to use
arrayBuf.bind();
indexBuf.bind();
// Offset for position
quintptr offset = 0;
// Tell OpenGL programmable pipeline how to locate vertex position data
int vertexLocation = program->attributeLocation("a_position");
program->enableAttributeArray(vertexLocation);
program->setAttributeBuffer(vertexLocation, GL_FLOAT, offset, 3, sizeof(VertexData));
// Offset for texture coordinate
offset += sizeof(QVector3D);
// Tell OpenGL programmable pipeline how to locate vertex texture coordinate data
int texcoordLocation = program->attributeLocation("a_texcoord");
program->enableAttributeArray(texcoordLocation);
program->setAttributeBuffer(texcoordLocation, GL_FLOAT, offset, 2, sizeof(VertexData));
// Draw cube geometry using indices from VBO 1
glDrawElements(GL_TRIANGLE_STRIP, 34, GL_UNSIGNED_SHORT, 0);
}
//! [2]