OpenGL ES 2.0-在顶点着色器中找不到属性

Question

I've looked for a while for an answer for this - but I'm not having much luck. All I'm trying to do is pass my normal data into my vertex shader. Positions are passing in correctly, however I'm receiving a "normal attribute not found" error when trying to load my shaders.

My ATTRIB values are enums.

I've created a cube in OpenGL ES 2.0 for Iphone development.

My Shader.vsh looks like this:

attribute vec4 normal;
attribute vec4 position;

varying vec4 colorVarying;

uniform mat4 mvp_matrix;

void main()
{
    //Trasform the vertex
    gl_Position = mvp_matrix * position;

    colorVarying = vec4(1.0, 1.0, 0.0, 0.0);
}

The part where I update attribute values in the drawframe looks like this:

// Update attribute values.
glVertexAttribPointer(ATTRIB_VERTEX, 3, GL_FLOAT, 0, 0, cubeVerticesStrip);
glEnableVertexAttribArray(ATTRIB_VERTEX);
glVertexAttribPointer(ATTRIB_NORMAL, 3, GL_FLOAT, 0, 0, cubeNormalsStrip);
glEnableVertexAttribArray(ATTRIB_NORMAL);

And the part where I bind these in my LoadShader function is like this:

glBindAttribLocation(program, ATTRIB_VERTEX, "position");
glBindAttribLocation(program, ATTRIB_NORMAL, "normal");

Again, the position works. But "normal" cannot be found. Any ideas?

Answer 1

normal isn't found because your GLSL compiler was smart. It saw that you didn't actually do something with normal , so it pretends it doesn't exist to save resources.

Also, your normal and position should be vec3 's since you're only passing 3 values. This isn't strictly required, but it is better form to make your inputs and attributes match.