为什么GLES20.glGetAttribLocation为不同的设备返回不同的值？

Question

我正在尝试使用OpenGL2.0并在3D空间中为Android设备创建多个立方体.

代码在某些设备中运行得很好,但在其他设备中却没有,我不知道为什么......(所有设备都支持OpenGL 2.0,并且有最新的Android版本[5.0或6.0])

我只知道问题是-1返回值(见下)

int vertexShader = loadGLShader(GLES20.GL_VERTEX_SHADER, R.raw.vertex);
int gridShader = loadGLShader(GLES20.GL_FRAGMENT_SHADER, R.raw.grid_fragment);
int passthroughShader = loadGLShader(GLES20.GL_FRAGMENT_SHADER, R.raw.fragment_color);

     cubeProgram1 = GLES20.glCreateProgram();
     GLES20.glAttachShader(cubeProgram1, vertexShader);
     GLES20.glAttachShader(cubeProgram1, passthroughShader);
     GLES20.glLinkProgram(cubeProgram1);
     GLES20.glUseProgram(cubeProgram1);

    cubePositionParam1 = GLES20.glGetAttribLocation(cubeProgram1, "a_Position");
    cubeNormalParam1 = GLES20.glGetAttribLocation(cubeProgram1, "a_Normal"); ----> Returns -1 Value
    cubeLightPosParam1 = GLES20.glGetUniformLocation(cubeProgram1, "u_LightPos");
    cubeModelParam1 = GLES20.glGetUniformLocation(cubeProgram1, "u_Model") cubeModelViewParam1 = GLES20.glGetUniformLocation(cubeProgram1, "u_MVMatrix");
    cubeModelViewProjectionParam1 = GLES20.glGetUniformLocation(cubeProgram1, "u_MVP");

....

 GLES20.glEnableVertexAttribArray(cubeNormalParam1); ---> Returns -1 ... 

cubeNormalParam1 = GLES20.glGetAttribLocation(cubeProgram1, "a_Normal");某些设备的返回值为2,其他设备的返回值为-1.那些有-1值,给出错误但没有运行的人......

我正在尝试看看vertex_shader是否有错误,但我看不出任何问题......

uniform mat4 u_Model;
uniform mat4 u_MVP;
uniform mat4 u_MVMatrix;
uniform vec3 u_LightPos;

attribute vec4 a_Position;
attribute vec4 a_Color;
attribute vec3 a_Normal;
attribute vec2 a_TexCoordinate;

varying vec4 v_Color;
varying vec3 v_Grid;
varying vec2 v_TexCoordinate;

void main() {
   v_Grid = vec3(u_Model * a_Position);


   vec3 modelViewVertex = vec3(u_MVMatrix * a_Position);
   vec3 modelViewNormal = vec3(u_MVMatrix * vec4(a_Normal, 0.0));

   float distance = length(u_LightPos - modelViewVertex);
   vec3 lightVector = normalize(u_LightPos - modelViewVertex);
   float diffuse = max(dot(modelViewNormal, lightVector), 0.5);

   diffuse = diffuse * (1.0 / (1.0 + (0.00001 * distance * distance)));
   v_Color = a_Color * diffuse;

   v_TexCoordinate = a_TexCoordinate;

   gl_Position = u_MVP * a_Position;
}

为什么会这样？是硬件？

任何解决方案来修复这个？

---

绘制立方体我是这样的:

public void drawCube1() {
        cubeNumber = 1;

        GLES20.glUseProgram(cubeProgram1);
        GLES20.glUniform3fv(cubeLightPosParam1, 1, lightPosInEyeSpace, 0);
        // Set the Model in the shader, used to calculate lighting
        GLES20.glUniformMatrix4fv(cubeModelParam1, 1, false, modelCube, 0);
        // Set the ModelView in the shader, used to calculate lighting
        GLES20.glUniformMatrix4fv(cubeModelViewParam1, 1, false, modelView, 0);
        // Set the ModelViewProjection matrix in the shader.
        GLES20.glUniformMatrix4fv(cubeModelViewProjectionParam1, 1, false, modelViewProjection1, 0);
        // Set the position of the cube
        GLES20.glVertexAttribPointer(
                cubePositionParam1, COORDS_PER_VERTEX, GLES20.GL_FLOAT, false, 0, cubeVertices);
        // Set the normal positions of the cube, again for shading
        GLES20.glVertexAttribPointer(cubeNormalParam1, 3, GLES20.GL_FLOAT, false, 0, cubeNormals);
        // Set the active texture unit to texture unit 0.
        GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
        // Bind the texture to this unit.
        GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, mTextura1);

        isLookingAtObject_Number(cubeNumber);

        // Tell the texture uniform sampler to use this texture in the shader by binding to texture unit 0.
        GLES20.glUniform1i(mTextureUniform, 0);

        GLES20.glVertexAttribPointer(mTextureCoordinate, 2, GLES20.GL_FLOAT, false, 0, cubeTexture);
        GLES20.glEnableVertexAttribArray(mTextureCoordinate);

        GLES20.glEnableVertexAttribArray(cubePositionParam1);
        GLES20.glEnableVertexAttribArray(cubeNormalParam1);

        GLES20.glDrawArrays(GLES20.GL_TRIANGLES, 0, 36);
        checkGLError("Drawing cube");
    }

Answer 1

Why GLES20.glGetAttribLocation returns different values for different devices?

...因为不同的设备将具有不同的硬件来设置绑定表,并且在某些情况下可以完全优化冗余计算并重新打包使用的属性以节省空间.这正是 API具有在运行时获取设备上的绑定位置的函数调用的原因; 如果它们是确定性常量,则根本不需要运行时调用...

它返回-1的事实不是错误; 它只是表明不需要属性(例如已定义,但可以优化,因为它不会影响片段像素颜色),所以这不应该导致任何问题.

但它确实意味着你不能安全地假设(例如)a_Position总是属性0,a_Color总是1,a_Normal总是2,等等.如果你在代码中硬编码那么你完全有可能上传错误的数据每个属性.您必须查询绑定位置以获取要使用的绑定编号(或使用OpenGL ES 3.x中添加的着色器端静态绑定).

哪个实际的GL API调用正在设置GL错误状态？