CODEWITHSUNDEEP
openglshader
Elektito
Elektito

Reputation: 4155

glDrawArrays: Same attribute for all triangles

I understand it is possible to set per-instance attributes when drawing with glDrawArraysInstanced and friends, so I was wondering if it's also possible to set an attribute once (i.e. per instance) for all vertices generated by glDrawArrays instead of setting them individually for each vertex?

Upvotes: 0

Views: 201

Answers (1)

Reto Koradi
Reto Koradi

Reputation: 54592

Certainly. For example if your attribute is a vec4, and the attribute location is attrLoc, you can use one of the following to set an attribute value that applies to the whole draw call:

glVertexAttrib4f(attrLoc, 1.0f, 2.0f, 3.0f, 4.0f);
glDrawArrays(...);

GLfloat attrVal[4] = {1.0f, 2.0f, 3.0f, 4.0f};
glVertexAttrib4fv(attrLoc, attrVal);
glDrawArrays(...);

There are equivalent calls for vectors with 1, 2, and 3 members.

Upvotes: 4

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