无法同时运行两个着色器程序，但是在单独使用时，每个程序都可以正常工作

Question

Ok对此扼杀了2天。我有一个小的GLES2 / Android应用程序...两个对象（都是正方形，但只有一个具有纹理坐标）。我有两个着色器程序，一个处理纹理及其坐标，另一个仅在片段着色器中使用颜色。

当我仅尝试渲染这些对象之一（并且仅编译和链接一个着色器程序）时，所有事情都可以正常工作，当我对两个对象都这样做时，仅渲染第二个对象（纹理正方形）。是的，在渲染相应的对象之前，我确实切换了着色器程序。一件事值得注意。当我调试时一个着色器程序中的顶点属性指针= 0 =另一个程序中的Texture属性指针下面是一些代码，感谢任何帮助

public abstract class SquareShader extends ShaderProgram {

public static int ShaderProgramObjectId;

public static int VertexPositionHandle;
public static int ColorUniformHandle;
public static int ProjectionMatrixHandle;
public static int ModelMatrixHandle;

public static void Initialize()
{
    ShaderProgramObjectId = LinkShaderProgram( R.raw.square_vertex_shader, 
 R.raw.square_fragment_shader);

    ColorUniformHandle = GLES20.glGetUniformLocation(ShaderProgramObjectId, "u_Color");
    ProjectionMatrixHandle = GLES20.glGetUniformLocation(ShaderProgramObjectId, 
   "u_ProjectionMatrix");
    ModelMatrixHandle = GLES20.glGetUniformLocation(ShaderProgramObjectId, "u_ModelMatrix");
    VertexPositionHandle = GLES20.glGetAttribLocation(ShaderProgramObjectId, "sq_VertexPosition");

    GLES20.glEnableVertexAttribArray(VertexPositionHandle);
}
}

public abstract class TextureShader extends ShaderProgram {
public static int ShaderProgramObjectId;

public static int VertexPositionHandle;
public static int TexturePositionHandle;
public static int ProjectionMatrixHandle;
public static int ModelMatrixHandle;
public static int TextureUnitHandle;

public static void Initialize()
{
    ShaderProgramObjectId = LinkShaderProgram( R.raw.texture_vertex_shader, 
    R.raw.texture_fragment_shader);

    ProjectionMatrixHandle = GLES20.glGetUniformLocation(ShaderProgramObjectId, 
    "u_ProjectionMatrix");
    ModelMatrixHandle = GLES20.glGetUniformLocation(ShaderProgramObjectId, "u_ModelMatrix");
    TextureUnitHandle = GLES20.glGetUniformLocation(ShaderProgramObjectId, "u_TextureUnit");

    VertexPositionHandle = GLES20.glGetAttribLocation(ShaderProgramObjectId, "a_VertexPosition");
    TexturePositionHandle = GLES20.glGetAttribLocation(ShaderProgramObjectId, "a_TexturePosition");

    GLES20.glEnableVertexAttribArray(VertexPositionHandle);
    GLES20.glEnableVertexAttribArray(TexturePositionHandle);

}
}

public void onDrawFrame(GL10 gl10) {
//Shade Programs are Initialized in (onSurfaceChanged)
    GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);

    GLES20.glUseProgram(SquareShader.ShaderProgramObjectId);
    GLES20.glUniformMatrix4fv(SquareShader.ProjectionMatrixHandle, 1, false, 
    DisplayUtility.ProjectionMatrix, 0);
    SquarePlain.Draw();



    GLES20.glUseProgram(TextureShader.ShaderProgramObjectId);
    GLES20.glUniformMatrix4fv(TextureShader.ProjectionMatrixHandle, 1, false, 
  DisplayUtility.ProjectionMatrix, 0);
    SquareTextured.Draw();
}


  //SquarePlain
  public static void Draw()
 {

    Matrix.setIdentityM(DisplayUtility.ModelMatrix, 0);
    Matrix.translateM(DisplayUtility.ModelMatrix, 0, 100 , 0, 0);
    GLES20.glUniformMatrix4fv(SquareShader.ModelMatrixHandle, 1, false, DisplayUtility.ModelMatrix, 0);

    GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, VBO_VertexBufferID[0]);
    GLES20.glVertexAttribPointer(SquareShader.VertexPositionHandle, COORDS_PER_VERTEX,
            GLES20.GL_FLOAT, false,
            vertexStride, 0);


    GLES20.glUniform4f(SquareShader.ColorUniformHandle, 0.0f, 0.0f, 1.0f, 1.0f);
    GLES20.glDrawElements(GLES20.GL_TRIANGLES, indices.length, GLES20.GL_UNSIGNED_SHORT, 
 indicesBuffer);
 }


 //SquareTextured 
 public static void Draw()
 {
    Matrix.setIdentityM(DisplayUtility.ModelMatrix, 0);
    Matrix.translateM(DisplayUtility.ModelMatrix, 0, 600 , 200, 0);

    GLES20.glUniformMatrix4fv(TextureShader.ModelMatrixHandle, 1, false, DisplayUtility.ModelMatrix, 0);

    //Bind vertices & Texture VBO

    GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, VBO_VertexBufferID[0]);
    GLES20.glVertexAttribPointer(TextureShader.VertexPositionHandle, COORDS_PER_VERTEX, GLES20.GL_FLOAT, false, vertexStride, 0);
    GLES20.glVertexAttribPointer(TextureShader.TexturePositionHandle, COORDS_PER_TexTure, GLES20.GL_FLOAT, false, vertexStride, COORDS_PER_VERTEX * Float.BYTES);


    //Switch Texture Buffer
    GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textureBufferId[0]);

    //Bind Indices VBO
    GLES20.glBindBuffer(GLES20.GL_ELEMENT_ARRAY_BUFFER, VBO_IndicesBufferID[0]);
    GLES20.glDrawElements(GLES20.GL_TRIANGLES, 6, GLES20.GL_UNSIGNED_SHORT, 0);
}

Answer 1

问题是绘制第一个对象时启用了纹理坐标的顶点属性数据数组（索引TexturePositionHandle）。注意，OpenGL是一个状态引擎，状态被保留直到再次更改，甚至超出帧。

[您必须启用着色器程序所需的通用顶点属性数组，并且必须确保在绘制对象时禁用其他顶点属性数组：

GLES20.glEnableVertexAttribArray(VertexPositionHandle);
GLES20.glDrawElements(GLES20.GL_TRIANGLES, indices.length, GLES20.GL_UNSIGNED_SHORT, 
                      indicesBuffer);
GLES20.glDisableVertexAttribArray(VertexPositionHandle);

GLES20.glEnableVertexAttribArray(VertexPositionHandle);
GLES20.glEnableVertexAttribArray(TexturePositionHandle);
GLES20.glDrawElements(GLES20.GL_TRIANGLES, 6, GLES20.GL_UNSIGNED_SHORT, 0);
GLES20.glDisableVertexAttribArray(VertexPositionHandle);
GLES20.glDisableVertexAttribArray(TexturePositionHandle);