CODEWITHSUNDEEP
copenglglsl
Javier Ramírez
Javier Ramírez

Reputation: 1011

how to use pointers in GLSL

I need to send a set of data to shader like.

//Application OpenGL

uniform vec3 *variable; 
variable = (uniform vec3 *)malloc(80 * sizeof(uniform vec3));  

//or    
uniform vec3 variable[80];

I need to send data such as indexes, and many other data.

Upvotes: 1

Views: 13779

Answers (1)

jameswilddev
jameswilddev

Reputation: 612

The latter case is correct. GLSL is built on having as simple and straightforward execution as possible. You cannot allocate memory in the shader, iterating is expensive. A well-written GLSL or HLSL shader takes in a fixed set of data, and outputs a fixed set of data. This makes it very fast to execute in parallel. This is my skeletal vertex shader.

 #version 110

uniform mat4 transform[ 32 ];

in int boneID;

void main()
{

    gl_FrontColor = gl_Color;
    gl_Position = transform[ boneID ] * gl_Vertex;

}

On the C/++ side, when calling glUniformMatrix4fv, point it to an array of several matrices and tell it how many there are, and it'll bring them through into GLSL as separate values.

Please note that my code is built on an old version of GLSL, and uses many now-deprecated elements such as gl_Vertex.

Upvotes: 3

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