Pass data from std::vector to uniform array in glsl

Question

I have a uniform in a shader like this:

uniform vec3 origins[10];

and a std::vector in my code like this:

std::vector<glm::vec3> origins;

that is filled with ten glm::vec3 elements.

Does anyone know how do I pass that to the shader? I thought:

GLint originsLoc = glGetUniformLocation(programID, "origins");
glUniform3fv(originsLoc, 10, origins.data());

would do it, but it wont compile. The error says there is no matching function for call to 'glUniform3fv'. How do I pass the data in the std::vector in a way that satisfies the glUniform3fv function?

"it doesnt work"...crash? Nothing drawn? Something unexpected drawn? — genpfault
– genpfault, Commented May 4, 2015 at 20:37
It wont compile. Should the code posted compile? The error says there is no matching function for call to 'glUniform3fv'. I edited the question with this info. — acrmuui
– acrmuui, Commented May 4, 2015 at 20:43
You should have to cast the pointer to a const GLfloat*. Without the cast, the function signature doesn't match. You should also include the *full compiler output. I'm guessing the actual error includes extra type/signature information that you have omitted, unfortunately. — Cornstalks
– Cornstalks, Commented May 4, 2015 at 21:05
Which version of OpenGL & GLSL are you using? Then if you are using versions 3.2+ then are you using the Core Profile Specification or the Compatibility Profile Specification? — Francis Cugler
– Francis Cugler, Commented May 5, 2015 at 1:56
What OS are you using and what IDE - Compiler are you using? — Francis Cugler
– Francis Cugler, Commented May 5, 2015 at 2:02

Yun · Accepted Answer · 2024-05-29 15:25:30Z

1

You should use a GLfloat and not a glm::vec3, but here it is anyway:

for (int i = 0; i != 10; i++) {
  GLint originsLoc = glGetUniformLocation(programID, "origins[i]");
  glUniform3f(originsLoc, origins[i].x, origins[i].y, origins[i].z);
}

edited May 29, 2024 at 15:25

Yun

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answered May 5, 2015 at 6:43

Mehdi

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acrmuui Over a year ago

Thanks for answering, that, and @Cornstalks pointed me in the right direction. What I ended up doing is this, which also works: glUniform3fv(originsLoc, origins.size(), reinterpret_cast<GLfloat *>(trackObstacle->obstaclesPopupNormals.data()))

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