osg.TextureRectangle

osg.TextureRectangle类封装了用于2D纹理映射的纹理。它提供了一种方便的方式来加载和使用图片、图形和其他纹理映射资源。

用法

创建一个新的osg.TextureRectangle对象:

osg::ref_ptr<osg::TextureRectangle> texture = new osg::TextureRectangle();

将一个图片文件加载到纹理中:

osg::ref_ptr<osg::Image> image = osgDB::readImageFile("image.png");
texture->setImage(image.get());

设置纹理的过滤方式:

texture->setFilter(osg::Texture::MIN_FILTER, osg::Texture::LINEAR);
texture->setFilter(osg::Texture::MAG_FILTER, osg::Texture::LINEAR);

将纹理应用于节点:

osg::ref_ptr<osg::Geometry> geometry = createRectangleGeometry();
osg::StateSet* state = geometry->getOrCreateStateSet();
state->setTextureAttributeAndModes(0, texture.get());

构造函数

• TextureRectangle()：默认构造函数。
• TextureRectangle(unsigned int texnum)：构造函数，使用指定的纹理单元号码。
• TextureRectangle(const TextureRectangle& rhs, const osg::CopyOp& copyop=osg::CopyOp::SHALLOW_COPY)：拷贝构造函数，使用指定纹理和拷贝操作。

成员函数

• void setImage(osg::Image* image)：设置纹理的图像。
• osg::Image* getImage()：获取纹理的图像。
• void setBorderColor(const osg::Vec4& color)：设置纹理边框的颜色。
• osg::Vec4 getBorderColor() const：获取纹理边框的颜色。
• void setWrap(osg::Texture::WrapParameter wrapS, osg::Texture::WrapParameter wrapT)：设置纹理的环绕方式。
• void setFilter(osg::Texture::FilterMode magFilter, osg::Texture::FilterMode minFilter)：设置纹理的过滤模式。
• void setMaxAnisotropy(float anisotropy)：设置纹理的最大各向异性。
• bool getUseHardwareMipMapGeneration() const：获取纹理是否使用硬件生成。
• void setUseHardwareMipMapGeneration(bool on_off)：设置纹理是否使用硬件生成。
• void setUnRefImageDataAfterApply(bool flag)：设置在应用纹理后是否释放图像数据。
• bool getUnRefImageDataAfterApply() const：获在应用纹理后是否释放图像数据。

示例代码

#include <osg/Geode>
#include <osg/Geometry>
#include <osg/TextureRectangle>
#include <osgDB/ReadFile>

osg::ref_ptr<osg::Geometry> createRectangleGeometry()
{
    osg::ref_ptr<osg::Geometry> geometry = new osg::Geometry();

    osg::Vec3Array* vertices = new osg::Vec3Array(4);
    (*vertices)[0] = osg::Vec3(-1.0f, -1.0f, 0.0f);
    (*vertices)[1] = osg::Vec3( 1.0f, -1.0f, 0.0f);
    (*vertices)[2] = osg::Vec3( 1.0f,  1.0f, 0.0f);
    (*vertices)[3] = osg::Vec3(-1.0f,  1.0f, 0.0f);
    geometry->setVertexArray(vertices);

    osg::Vec2Array* texcoords = new osg::Vec2Array(4);
    (*texcoords)[0] = osg::Vec2(0.0f, 0.0f);
    (*texcoords)[1] = osg::Vec2(1.0f, 0.0f);
    (*texcoords)[2] = osg::Vec2(1.0f, 1.0f);
    (*texcoords)[3] = osg::Vec2(0.0f, 1.0f);
    geometry->setTexCoordArray(0, texcoords);

    osg::DrawElementsUShort* indices = new osg::DrawElementsUShort(osg::PrimitiveSet::QUADS, 4);
    (*indices)[0] = 0;
    (*indices)[1] = 1;
    (*indices)[2] = 2;
    (*indices)[3] = 3;
    geometry->addPrimitiveSet(indices);

    return geometry;
}

int main(int argc, char** argv)
{
    osg::ref_ptr<osg::Referenced> init = osg::Referenced::newRef();
    osg::ref_ptr<osg::GraphicsContext::Traits> traits = new osg::GraphicsContext::Traits();
    traits->windowName = "osgtexrect";
    traits->screenNum = 0;
    traits->x = 50;
    traits->y = 50;
    traits->width = 800;
    traits->height = 600;
    osg::ref_ptr<osg::GraphicsContext> gc = osg::GraphicsContext::createGraphicsContext(traits.get());
    osg::ref_ptr<osg::Camera> camera = new osg::Camera();
    camera->setClearColor(osg::Vec4(0.5, 0.5, 1.0, 1.0));
    camera->setGraphicsContext(gc.get());
    camera->setViewport(0, 0, traits->width, traits->height);
    camera->setProjectionMatrixAsPerspective(45.0, (double)traits->width / (double)traits->height, 0.1, 100.0);
    osg::ref_ptr<osg::Group> root = new osg::Group();
    root->addChild(camera);

    osg::ref_ptr<osg::Geometry> geometry = createRectangleGeometry();

    osg::ref_ptr<osg::TextureRectangle> texture = new osg::TextureRectangle();
    osg::ref_ptr<osg::Image> image = osgDB::readImageFile("image.png");
    texture->setImage(image.get());
    texture->setFilter(osg::Texture::MIN_FILTER, osg::Texture::LINEAR);
    texture->setFilter(osg::Texture::MAG_FILTER, osg::Texture::LINEAR);

    osg::StateSet* state = geometry->getOrCreateStateSet();
    state->setTextureAttributeAndModes(0, texture.get());

    osg::ref_ptr<osg::Geode> geode = new osg::Geode();
    geode->addDrawable(geometry.get());
    root->addChild(geode.get());

    osgViewer::Viewer viewer;
    viewer.setSceneData(root.get());
    return viewer.run();
}