Details
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Bug
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Resolution: Invalid
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P3: Somewhat important
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None
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6.4.1
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None
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Kubunt 22.04 + NVidia v520 drivers
Qt from binary packages.
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Linux/X11
Description
I want to create a float32 depth buffer for OpenGl ES 3 (and later WebGL via webassembly). I got it working with opengl commands, but not with the QOpenGLTexture class.
These are the relevant opengl calls:
f->glGenTextures(1, &m_frame_buffer_depth);
f->glBindTexture(GL_TEXTURE_2D, m_frame_buffer_depth);
{
const auto level = 0;
const auto internalFormat = GL_DEPTH_COMPONENT32F;
const auto border = 0;
const auto format = GL_DEPTH_COMPONENT;
const auto type = GL_FLOAT;
const auto data = nullptr;
f->glTexImage2D(GL_TEXTURE_2D, level, internalFormat, 4, 4, border, format, type, data);
}
I tried to switch to QOpenGLTexture for a nicer API:
m_depth_texture = std::make_unique<QOpenGLTexture>(QOpenGLTexture::Target::Target2D); m_depth_texture->setFormat(QOpenGLTexture::TextureFormat::D32F); m_depth_texture->setSize(800, 600); m_depth_texture->allocateStorage(QOpenGLTexture::Depth, QOpenGLTexture::PixelType::Float32);
unfortunately, QOpenGLTexture::Depth and QOpenGLTexture::PixelType::Float32 get ignored and creating the texture fails. The reason is, that Qt tries to allocate immutable storage, and ignores the parameters when doing so:
void QOpenGLTexturePrivate::allocateStorage(QOpenGLTexture::PixelFormat pixelFormat, QOpenGLTexture::PixelType pixelType) { // Resolve the actual number of mipmap levels we can use mipLevels = evaluateMipLevels(); if (isUsingImmutableStorage()) allocateImmutableStorage(); // -> debugger stepped in this one. else allocateMutableStorage(pixelFormat, pixelType); }