How do I pass an array of struct to shader

Question

i have a struct

struct distance
{
    int dist[5];
};

and its used as an array

distance dist[100];

How can i pass this to my tessellation control shader?

shader:

 #version 410 core

struct distance
{
    int dist[5];
};

uniform distance myDistances[100];

layout (vertices = 16) out;

void main(void)
{
    uint id = gl_InvocationID;

    if (id == 0)
    {
        gl_TessLevelInner[0] = myDistances[gl_PrimitiveID].dist[4];
        gl_TessLevelInner[1] = myDistances[gl_PrimitiveID].dist[4];
        gl_TessLevelOuter[0] = myDistances[gl_PrimitiveID].dist[0];
        gl_TessLevelOuter[1] = myDistances[gl_PrimitiveID].dist[1];
        gl_TessLevelOuter[2] = myDistances[gl_PrimitiveID].dist[2];
        gl_TessLevelOuter[3] = myDistances[gl_PrimitiveID].dist[3];
    }

    gl_out[gl_InvocationID].gl_Position = gl_in[id].gl_Position;
}

application uniform definition:

struct
    {
        struct
        {
            int     mv_matrix;
            int     proj_matrix;
            int     mvp;
            int     dist;
        } patch;
        struct
        {
            int     draw_color;
            int     mvp;
        } control_point;
    } uniforms;

in my main

glUniformMatrix4fv(uniforms.patch.mv_matrix, 1, GL_FALSE, mv_matrix);
    glUniformMatrix4fv(uniforms.patch.proj_matrix, 1, GL_FALSE, proj_matrix);
    glUniformMatrix4fv(uniforms.patch.mvp, 1, GL_FALSE, proj_matrix * mv_matrix);
    for(int i=0; i<100; i++)
    {
        for(int j=0; j<5; j++)
        {
            glGetUniformLocation(program, "myDistances[i].dist[j]");
            glUniform1i(uniforms.patch.dist, ocean.detail[i].dist[j]);
        }
    }

BDL · Accepted Answer · 2014-12-18 09:19:24Z

1

Under the assumption that you want to pass the data as a uniforms: You can use a similar struct than in C++. The following code could be your shader:

struct distance
{
    int dist[5];
};

uniform distance myDistances[100];

void main()
{
     ....
}

In you application you can access the struct by

glUniform1i(..., "myDistances[i].dist[j]")

where i =[0-99] and j = [1-5] (or by glUniform1iv with the same uniform name).

answered Dec 18, 2014 at 9:19

BDL

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3 Comments

user2155533 Over a year ago

Yes i'd like to pass it in as a uniform. The problem is i'm not sure how to set up the uniform in my applications main.

user2155533 Over a year ago

glUniform1iv(uniforms.patch.dist, 100, ocean.detail); is complaining that ist not an GLint

BDL Over a year ago

Basically yes, but your result of glGetUniform isn't stored anywhere and you have to replace i and j in "myDistances[i].dist[j]" with the value of your variable. Something like "myDistances[" + i + "].dist[" + j + "]".

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