Force to gles2 (OpenGL ES 2.0)

[fightimbs]

Hi All


I'm making an app that should be used with OpenGL ES 2.0. I have taken an example gles2 but modifying it has automatically changed to gles3. I need it to be gles2.
How do I force it to compile gles2? I use Qt5.7 but originally example is Qt4.8.

std::string glVersion = reinterpret_cast<const char*>(glGetString(GL_VERSION));
std::string glslVer = reinterpret_cast<const char*>(glGetString(GL_SHADING_LANGUAGE_VERSION));
qDebug("glVer: %s\nglslVer: %s", glVersion.c_str(), glslVer.c_str());

std::string glVersion = reinterpret_cast<const char*>(glGetString(GL_VERSION));
std::string glslVer = reinterpret_cast<const char*>(glGetString(GL_SHADING_LANGUAGE_VERSION));
qDebug("glVer: %s\nglslVer: %s", glVersion.c_str(), glslVer.c_str());

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glVer: OpenGL ES 3.0 Mesa 12.0.6
glslVer: OpenGL ES GLSL ES 3.00

Thank you.

[fightimbs]

I tested hellogl_es2 example and works! But my app use same include and not works.

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Added after 10 minutes:

We start from an example of Qt (hellogl_es2) and we added texture to the ground, some billboard icons that rotate and updated the app to Qt5.7. While I only use gles2 functions in a qDebug I see that Qt5.7 is compiling for gles3.

std::string glVersion = reinterpret_cast<const char*>(glGetString(GL_VERSION));
std::string glslVer = reinterpret_cast<const char*>(glGetString(GL_SHADING_LANGUAGE_VERSION));
qDebug("glVer: %s\nglslVer: %s", glVersion.c_str(), glslVer.c_str());

glVer: OpenGL ES 3.0 Mesa 12.0.6
glslVer: OpenGL ES GLSL ES 3.00

hellogl_es2 qt example works fine on both but in my app only black box is seen with nothing.}

GPU supports Open GL ES 3.1
Yocto distribution has partial support for GL ES 3.0
but Qt toolchain for crosscopile supports only GL ES 2.0

How do I force Qt to compile on gles2?

I've tried code like the following and it returns "2.0" but compiles to gles3.

QSurfaceFormat format;
format.setVersion(2,0);

int majorVersion = format.majorVersion();
int minorVersion = format.minorVersion();
qDebug("Major Version %d", majorVersion);
qDebug("Minor Version %d", minorVersion);


I appreciate who can help me.

Greetings.

[wysota]

OpenGLES 3.0 is backward compatible with OpenGLES 2.0 so if you only use 2.0 code in your shaders, it should be working. Are you sure the problem is not elsewhere?