绘制元素后无法绘制数组

Cannot draw arrays after drawing elements

本文关键字：绘制 数组 元素      更新时间：2023-10-16

我有一个巨大的彩色表面（超过 130 万个索引）被绘制出来。此表面使用"彩色顶点"进行索引。每当我尝试在缓冲三角形（彩色顶点）之后绘制非缓冲三角形时，都不会显示非缓冲三角形。

如果我跳过绘制表面（缓冲三角形），则非缓冲三角形将按预期绘制。

绘制缓冲顶点：

// Bind array buffer
arrayBuffer->bind();
// Set position of vertices
int posLocation = program->attributeLocation("a_position");
program->enableAttributeArray(posLocation);
program->setAttributeBuffer(posLocation, GL_FLOAT, 0, 3, sizeof(ColoredVertex));
// Set color of vertices
int colorLocation = program->attributeLocation("a_color");
program->enableAttributeArray(colorLocation);
program->setAttributeBuffer(colorLocation, GL_FLOAT, sizeof(QVector3D), 3, sizeof(ColoredVertex));
(GLfloat) 0.0);
// Bind index buffer and draw triangles
indexBuffer->bind();
glDrawElements(GL_TRIANGLES, indicesCount(), GL_UNSIGNED_INT, 0);

绘制非缓冲顶点（面）：

if (faces.size() == 0) {
    qDebug("Tried to draw a textured block with no faces.");
    return;
}
int posLocation = program->attributeLocation("a_position");
int texcoordLocation = program->attributeLocation("a_texcoord");
// Draw faces
QHashIterator<Block::Side, Face> iterator(faces);
while (iterator.hasNext()) {
    Face face = iterator.next().value();
    program->setAttributeArray(posLocation, face.coordinates.constData());
    program->enableAttributeArray(posLocation);
    program->setAttributeArray(texcoordLocation, face.textureCoordinates.constData());
    program->enableAttributeArray(texcoordLocation);
    glDrawArrays(GL_LINES, 0, 6);
}

该错误似乎是由于未正确禁用属性数组和释放缓冲区对象。以下代码按预期工作。

绘制缓冲顶点：

// Bind array buffer
arrayBuffer->bind();
int posLocation = program->attributeLocation("a_position");
int colorLocation = program->attributeLocation("a_color");
program->enableAttributeArray("a_position");
program->enableAttributeArray("a_color");
program->setAttributeBuffer(posLocation, GL_FLOAT, 0, 3, sizeof(ColoredVertex));
program->setAttributeBuffer(colorLocation, GL_FLOAT, sizeof(QVector3D), 3, sizeof(ColoredVertex));
// Bind index buffer and draw triangles
indexBuffer->bind();
glDrawElements(GL_TRIANGLES, indicesCount(), GL_UNSIGNED_INT, 0);
indexBuffer->release();
program->disableAttributeArray(posLocation);
program->disableAttributeArray(colorLocation);
arrayBuffer->release();

绘制非缓冲顶点（面）：

if (faces.size() == 0) {
    qDebug("Tried to draw a textured block with no faces.");
    return;
}
int posLocation = program->attributeLocation("a_position");
int texcoordLocation = program->attributeLocation("a_texcoord");
program->enableAttributeArray(posLocation);
program->enableAttributeArray(posLocation);
program->enableAttributeArray(texcoordLocation);
program->enableAttributeArray(texcoordLocation);
// Draw faces
QHashIterator<Block::Side, Face> iterator(faces);
while (iterator.hasNext()) {
    Face face = iterator.next().value();
    program->setAttributeArray(posLocation, face.coordinates.constData());
    program->setAttributeArray(texcoordLocation, face.textureCoordinates.constData());
    glDrawArrays(GL_TRIANGLES, 0, face.coordinates.size());
}
program->disableAttributeArray(posLocation);
program->disableAttributeArray(texcoordLocation);
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