Why there is no version on Qt shader program? - c++

Question

From https://learnopengl.com/Getting-started/Shaders I read:
Shaders always begin with a version declaration, ...
But on OpenGL Window Example there is no version on shader code. What's the version then?
static const char *vertexShaderSource =
"attribute highp vec4 posAttr;\n"
"attribute lowp vec4 colAttr;\n"
"varying lowp vec4 col;\n"
"uniform highp mat4 matrix;\n"
"void main() {\n"
" col = colAttr;\n"
" gl_Position = matrix * posAttr;\n"
"}\n";
static const char *fragmentShaderSource =
"varying lowp vec4 col;\n"
"void main() {\n"
" gl_FragColor = col;\n"
"}\n";
Following seems to be related: How to Convert GLSL #version 330 core to GLSL ES #version 100?

Answer 1

In qt 5.12.2 source file : qopenglshaderprogram.cpp
LINE 604:
bool QOpenGLShader::compileSourceCode(const char *source){
Q_D(QOpenGLShader);
// This method breaks the shader code into two parts:
// 1. Up to and including an optional #version directive.
// 2. The rest.
// If a #version directive exists, qualifierDefines and redefineHighp
// are inserted after. Otherwise they are inserted right at the start.
// In both cases a #line directive is appended in order to compensate
// for line number changes in case of compiler errors.
if (d->shaderGuard && d->shaderGuard->id() && source) {
const QVersionDirectivePosition versionDirectivePosition = findVersionDirectivePosition(source);
QVarLengthArray<const char *, 5> sourceChunks;
QVarLengthArray<GLint, 5> sourceChunkLengths;
QOpenGLContext *ctx = QOpenGLContext::currentContext();
if (versionDirectivePosition.hasPosition()) {
// Append source up to and including the #version directive
sourceChunks.append(source);
sourceChunkLengths.append(GLint(versionDirectivePosition.position));
} else {
// QTBUG-55733: Intel on Windows with Compatibility profile requires a #version always
if (ctx->format().profile() == QSurfaceFormat::CompatibilityProfile) {
const char *vendor = reinterpret_cast<const char *>(ctx->functions()->glGetString(GL_VENDOR));
if (vendor && !strcmp(vendor, "Intel")) {
static const char version110[] = "#version 110\n";
sourceChunks.append(version110);
sourceChunkLengths.append(GLint(sizeof(version110)) - 1);
}
}
}
and
static QVersionDirectivePosition findVersionDirectivePosition(const char *source){
Q_ASSERT(source);
// According to the GLSL spec the #version directive must not be
// preceded by anything but whitespace and comments.
// In order to not get confused by #version directives within a
// multiline comment, we need to do some minimal comment parsing
// while searching for the directive.
If version is not available, "#version 110\n" will be added.
static const char version110[] = "#version 110\n";
sourceChunks.append(version110);