mirror of
https://github.com/crystalidea/qt6windows7.git
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127 lines
4.9 KiB
C++
127 lines
4.9 KiB
C++
// Copyright (C) 2022 The Qt Company Ltd.
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// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
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#include "geometryengine.h"
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#include <QVector2D>
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#include <QVector3D>
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struct VertexData
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{
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QVector3D position;
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QVector2D texCoord;
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};
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GeometryEngine::GeometryEngine()
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: indexBuf(QOpenGLBuffer::IndexBuffer)
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{
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initializeOpenGLFunctions();
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// Generate 2 VBOs
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arrayBuf.create();
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indexBuf.create();
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// Initializes cube geometry and transfers it to VBOs
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initCubeGeometry();
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}
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GeometryEngine::~GeometryEngine()
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{
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arrayBuf.destroy();
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indexBuf.destroy();
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}
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void GeometryEngine::initCubeGeometry()
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{
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// For cube we would need only 8 vertices but we have to
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// duplicate vertex for each face because texture coordinate
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// is different.
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VertexData vertices[] = {
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// Vertex data for face 0
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{QVector3D(-1.0f, -1.0f, 1.0f), QVector2D(0.0f, 0.0f)}, // v0
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{QVector3D( 1.0f, -1.0f, 1.0f), QVector2D(0.33f, 0.0f)}, // v1
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{QVector3D(-1.0f, 1.0f, 1.0f), QVector2D(0.0f, 0.5f)}, // v2
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{QVector3D( 1.0f, 1.0f, 1.0f), QVector2D(0.33f, 0.5f)}, // v3
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// Vertex data for face 1
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{QVector3D( 1.0f, -1.0f, 1.0f), QVector2D( 0.0f, 0.5f)}, // v4
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{QVector3D( 1.0f, -1.0f, -1.0f), QVector2D(0.33f, 0.5f)}, // v5
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{QVector3D( 1.0f, 1.0f, 1.0f), QVector2D(0.0f, 1.0f)}, // v6
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{QVector3D( 1.0f, 1.0f, -1.0f), QVector2D(0.33f, 1.0f)}, // v7
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// Vertex data for face 2
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{QVector3D( 1.0f, -1.0f, -1.0f), QVector2D(0.66f, 0.5f)}, // v8
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{QVector3D(-1.0f, -1.0f, -1.0f), QVector2D(1.0f, 0.5f)}, // v9
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{QVector3D( 1.0f, 1.0f, -1.0f), QVector2D(0.66f, 1.0f)}, // v10
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{QVector3D(-1.0f, 1.0f, -1.0f), QVector2D(1.0f, 1.0f)}, // v11
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// Vertex data for face 3
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{QVector3D(-1.0f, -1.0f, -1.0f), QVector2D(0.66f, 0.0f)}, // v12
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{QVector3D(-1.0f, -1.0f, 1.0f), QVector2D(1.0f, 0.0f)}, // v13
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{QVector3D(-1.0f, 1.0f, -1.0f), QVector2D(0.66f, 0.5f)}, // v14
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{QVector3D(-1.0f, 1.0f, 1.0f), QVector2D(1.0f, 0.5f)}, // v15
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// Vertex data for face 4
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{QVector3D(-1.0f, -1.0f, -1.0f), QVector2D(0.33f, 0.0f)}, // v16
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{QVector3D( 1.0f, -1.0f, -1.0f), QVector2D(0.66f, 0.0f)}, // v17
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{QVector3D(-1.0f, -1.0f, 1.0f), QVector2D(0.33f, 0.5f)}, // v18
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{QVector3D( 1.0f, -1.0f, 1.0f), QVector2D(0.66f, 0.5f)}, // v19
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// Vertex data for face 5
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{QVector3D(-1.0f, 1.0f, 1.0f), QVector2D(0.33f, 0.5f)}, // v20
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{QVector3D( 1.0f, 1.0f, 1.0f), QVector2D(0.66f, 0.5f)}, // v21
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{QVector3D(-1.0f, 1.0f, -1.0f), QVector2D(0.33f, 1.0f)}, // v22
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{QVector3D( 1.0f, 1.0f, -1.0f), QVector2D(0.66f, 1.0f)} // v23
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};
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// Indices for drawing cube faces using triangle strips.
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// Triangle strips can be connected by duplicating indices
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// between the strips. If connecting strips have opposite
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// vertex order then last index of the first strip and first
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// index of the second strip needs to be duplicated. If
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// connecting strips have same vertex order then only last
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// index of the first strip needs to be duplicated.
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GLushort indices[] = {
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0, 1, 2, 3, 3, // Face 0 - triangle strip ( v0, v1, v2, v3)
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4, 4, 5, 6, 7, 7, // Face 1 - triangle strip ( v4, v5, v6, v7)
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8, 8, 9, 10, 11, 11, // Face 2 - triangle strip ( v8, v9, v10, v11)
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12, 12, 13, 14, 15, 15, // Face 3 - triangle strip (v12, v13, v14, v15)
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16, 16, 17, 18, 19, 19, // Face 4 - triangle strip (v16, v17, v18, v19)
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20, 20, 21, 22, 23 // Face 5 - triangle strip (v20, v21, v22, v23)
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};
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// Transfer vertex data to VBO 0
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arrayBuf.bind();
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arrayBuf.allocate(vertices, 24 * sizeof(VertexData));
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// Transfer index data to VBO 1
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indexBuf.bind();
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indexBuf.allocate(indices, 34 * sizeof(GLushort));
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}
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void GeometryEngine::drawCubeGeometry(QOpenGLShaderProgram *program)
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{
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// Tell OpenGL which VBOs to use
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arrayBuf.bind();
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indexBuf.bind();
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// Offset for position
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quintptr offset = 0;
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// Tell OpenGL programmable pipeline how to locate vertex position data
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int vertexLocation = program->attributeLocation("a_position");
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program->enableAttributeArray(vertexLocation);
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program->setAttributeBuffer(vertexLocation, GL_FLOAT, offset, 3, sizeof(VertexData));
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// Offset for texture coordinate
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offset += sizeof(QVector3D);
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// Tell OpenGL programmable pipeline how to locate vertex texture coordinate data
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int texcoordLocation = program->attributeLocation("a_texcoord");
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program->enableAttributeArray(texcoordLocation);
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program->setAttributeBuffer(texcoordLocation, GL_FLOAT, offset, 2, sizeof(VertexData));
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// Draw cube geometry using indices from VBO 1
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glDrawElements(GL_TRIANGLE_STRIP, 34, GL_UNSIGNED_SHORT, nullptr);
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}
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