I want to send a series of integer to the geometry shader, while the data will be modified every frame.

But when I try to retrive the sampleBuffer in geometry shader, it seems to keep output zero.

Am I using Texture Buffer wrong, or the TBO itself just can't be used as GL_DYNAMIC_DRAW?

Init Texture Buffer

void InitialTBO() {
    int index_tbo_reserved_size = 5000;
    glGenBuffers(1, &index_tbo);
    glBindBuffer(GL_TEXTURE_BUFFER, index_tbo);
    glBufferData(GL_TEXTURE_BUFFER, index_tbo_reserved_size * sizeof(GLint), NULL, GL_DYNAMIC_DRAW);
    glGenTextures(1, &index_tbo_tex);


void RenderChunkDataCone(Primitive* primitive) {
    Program* shaders = primitive->shaders;


    glBindBuffer(GL_TEXTURE_BUFFER, this->index_tbo);
    glBufferSubData(GL_TEXTURE_BUFFER, 0, sizeof(GLint)*index_tbo_data.size(), index_tbo_data.data());
    glBindTexture(GL_TEXTURE_BUFFER, this->index_tbo_tex);
    glTexBuffer(GL_TEXTURE_BUFFER, GL_R32I, this->index_tbo);
    shaders->setUniform("index_tex", 0);

    glDrawElements(primitive->drawType, primitive->drawCount * primitive->drawCount_Inner, GL_UNSIGNED_INT, 0);


Geometry Shader

#version 460 core
uniform samplerBuffer index_tex;
vec3 render_primitive(vec3 position){
    int status = int(texelFetch(index_tex, 0).r);
        return vec3(0,10,10);
    else if(status==1)
        return vec3(10,0,0);
    else if(status==2)
        return vec3(0,0,10);

void main() {
    vec4 position =gl_in[0].gl_Position;
    vec3 returnedValue = render_primitive(position.xyz);

I've confirmed the index_tbo[0] is 1, But the returnedValue outputed by shader will always be (0,10,10) as the value index_tex[0] received seems to be 0.


1 Answer 1



glTexBuffer(GL_TEXTURE_BUFFER, GL_R32I, this->index_tbo);
uniform samplerBuffer index_tex;

Do not match. If the texture is a signed integer texture, then the sampler type needs to match. It should be isamplerBuffer, and you won't need to do the cast.


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