为什么GLES20.glGetAttribLocation为不同的设备返回不同的值? [英] Why GLES20.glGetAttribLocation returns different values for different devices?

问题描述

我正在尝试使用OpenGL2.0，并在3D空间中为Android设备创建多个多维数据集.

I'm trying using OpenGL2.0 and create multiple cubes in 3D space, for android devices.

它的代码可以在某些设备上完美运行，但在其他设备上则无法运行，我也不知道为什么...(所有设备都支持OpenGL 2.0，并且具有最新的android版本[5.0或6.0])

The code it runs perfectly in some devices, but not in others, and i don't know why... (All devices have OpenGL 2.0 supported, and have recent android versions [5.0 or 6.0])

我只知道问题出在-1返回值中(见下)

I only know that the problem is in a -1 return value (see down)

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 ... 

在某些设备中，cubeNormalParam1 = GLES20.glGetAttribLocation(cubeProgram1, "a_Normal");返回值2，在其他设备中返回-1.那些拥有-1值的人会出错并且无法运行...

The cubeNormalParam1 = GLES20.glGetAttribLocation(cubeProgram1, "a_Normal"); returns value 2 in some devices, and -1 in others. Those who have -1 value, give error and doesn't run...

我正在尝试查看vertex_shader是否有错误，但是我看不到任何问题...

I'm trying see if the vertex_shader have errors but i can't see any problems...

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?是硬件吗?

Why this happen? Is the Hardware?

有解决此问题的解决方案吗?

Any Solution to fix this?

要绘制多维数据集，我要这样做:

To draw Cube i've this:

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");
    }

推荐答案

解决方案-与-1值相乘

The Solution - multiplying with -1 value

 ... = GLES20.glGetAttribLocation(cubeProgram1, "a_Normal") * -1;

或

int value;
if( GLES20.glGetAttribLocation(cubeProgram1, "a_Normal") < 0){
      value = -1;
}
else {
      value = 1;
}

... = GLES20.glGetAttribLocation(cubeProgram1, "a_Normal") * value;

这不是最好的解决方案，但现在可以了.

Is not the best solution, but now it works.

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