Unable to use separate shader programs "<program> object is not successfully linked." - c++

Question

const char *vs_source =
"#version 440\n\
layout(location = 0) in vec2 position;\n\
layout(location = 1) in float offset;\n\
void main() {\n\
vec2 new_pos = vec2(position.x + offset,position.y);\n\
gl_Position = vec4(new_pos,0,1);\n\
}";
const char *fs_source =
"#version 440\n\
out vec4 out_color;\n\
void main() {\n\
out_color = vec4(1,0,0,1);\n\
}";
auto vsp = createShaderProgram(GL_VERTEX_SHADER,1,&vs_source);
auto fsp = createShaderProgram(GL_FRAGMENT_SHADER,1,&fs_source);
GLuint pipeline;
glGenProgramPipelines(1,&pipeline);
glUseProgramStages(pipeline, GL_VERTEX_SHADER_BIT , vsp.handle);
glUseProgramStages(pipeline, GL_FRAGMENT_SHADER_BIT, fsp.handle);
glBindProgramPipeline(pipeline);
with
struct Program{
GLuint handle;
};
Program createShaderProgram(GLenum type,
GLsizei count,
const char **strings){
const GLuint shader = glCreateShader(type);
if (shader) {
glShaderSource(shader, count, strings, NULL);
glCompileShader(shader);
const GLuint program = glCreateProgram();
if (program) {
GLint compiled = GL_FALSE;
glGetShaderiv(shader, GL_COMPILE_STATUS, &compiled);
glProgramParameteri(program, GL_PROGRAM_SEPARABLE, GL_TRUE);
if (compiled) {
glAttachShader(program, shader);
glLinkProgram(program);
glDetachShader(program, shader);
}
else{
/* append-shader-info-log-to-program-info-log */
GLint infoLogLength;
glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &infoLogLength);
GLchar* infoLog = new GLchar[infoLogLength + 1];
glGetShaderInfoLog(shader, infoLogLength, NULL, infoLog);
std::cout << "ERROR: Unable to compile shader" << std::endl << infoLog << std::endl;
delete[] infoLog;
}
}
glDeleteShader(shader);
return Program{program};
} else {
return Program{0};
}
}
OpenGL tells me that
message: GL_INVALID_OPERATION error generated. <program> object is not successfully linked.
type: ERROR
HIGH
and I am not sure why. If I link it the old way and only create one program it works perfectly.
I am guessing I have misused the the new pipeline system?
I should also mention that the error only appears when I start to call
glUseProgramStages(pipeline, GL_VERTEX_SHADER_BIT , vsp.handle);
glUseProgramStages(pipeline, GL_FRAGMENT_SHADER_BIT, fsp.handle);
Could this be a driver bug?

Answer 1

Solved it. The vertex shader didn't link. I had to redeclare gl_Position.
const char *vs_source =
"#version 440\n\
layout(location = 0) in vec2 position;\n\
layout(location = 1) in float offset;\n\
out gl_PerVertex\n\
{\n\
vec4 gl_Position;\n\
float gl_PointSize;\n\
float gl_ClipDistance[];\n\
};\n\
void main() {\n\
vec2 new_pos = vec2(position.x + offset,position.y);\n\
gl_Position = vec4(new_pos,0,1);\n\
}";