通过opengl中的纹理传递数组数据

Question

所以我正在尝试将一堆矢量传递给片段着色器，显然我应该使用 1d 纹理来完成。但是如果我尝试访问传递的向量，这些值不是我所期望的。

我应该如何索引 texture() 函数？

传递纹理：

std::vector<vec3> triangles;
//triangles is already filled by this point
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_1D, texture);        
glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexImage1D(GL_TEXTURE_1D, 0, GL_RGB16F, Object::triangles.size(), 0, GL_RGB, GL_FLOAT, &Object::triangles[0]);

GLint textureLoc =  glGetUniformLocation( getId(), "triangles" );
glUniform1f(textureLoc, 0);

setUniform((int)Object::triangles.size(), "triCount");

glBindVertexArray(vao);
glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
//draw a rectangle from -1,-1 to 1,1

片段着色器代码：

uniform sampler1D triangles;
uniform int triCount;

struct Triangle{
            vec3 a,b,c;
            vec3 normal;
};

void main(){
  for(int i = 0;i < triCount;i++){//for each triangle
    Triangle triangle;
    //set the points of the triangle
    triangle.a = vec3(texture(triangles,i));
    triangle.b = vec3(texture(triangles,i++));
    triangle.c = vec3(texture(triangles,i++));
    //set the normal vector of the triangle
    triangle.normal = vec3(texture(triangles,i++));

    //then i do stuff with the current triangle and return a color 
  }
}

该数组包含 3 个点和一组三角形的法向量，这就是我以这种方式读取纹理的原因。

编辑： glGetTexImage 确认传递的纹理是正确的。

Answer 1

当使用 texture, the texture coordinates are floating point values in the range [0.0, 1.0]. Use texelFetch 从具有 [0, width] 范围内的整数纹理坐标的纹理执行单个 Texel 查找时：

triangle.a      = texelFetch(triangles, i*4,   0).xyz;
triangle.b      = texelFetch(triangles, i*4+1, 0).xyz;
triangle.c      = texelFetch(triangles, i*4+2, 0).xyz;
triangle.normal = texelFetch(triangles, i*4+3, 0).xyz;

请注意，您的着色器代码中的 Texel 索引计算不正确。

或者，您可以通过索引除以纹理宽度来计算纹理坐标。纹理的大小可以通过 textureSize:

获得

float width = float(textureSize(triangles, 0));

triangle.a      = texture(triangles, (float(i*4)+0.5) / width).xyz;
triangle.b      = texture(triangles, (float(i*4)+1.5) / width).xyz;
triangle.c      = texture(triangles, (float(i*4)+2.5) / width).xyz;
triangle.normal = texture(triangles, (float(i*4)+3.5) / width).xyz;

通过opengl中的纹理传递数组数据

Passing array data through textures in opengl

c++

opengl

glsl

fragment-shader