在opengl ES2.0中以全屏居中和正确的比例渲染纹理

Question

我正在加载一个位图到渲染器类中，我想用正确的比例和尽可能大的比例来渲染屏幕中心的纹理

顶点和纹理数据：

private final float[]mVerticesData={-1f,1f,0.0f,//位置0.0.0f,0.0f,//TexCoord 0-1f,-1f,0.0f,//位置1.0.0f,1.0f,//TexCoord 1 1f,-1f,0.0f,//位置2 1.0 f,1.0 f,//TexCoord 2 1f,1f,0.0f,//位置3 1.0 f,0.0f//TexCoord 3}；

private final short[] mIndicesData =
{ 
        0, 1, 2, 0, 2, 3 
};

和绘制方法：

public void onDrawFrame(GL10 glUnused）{

    // Set the viewport
    GLES20.glViewport(0, 0, bitmap.width, bitmap.height);

    // Clear the color buffer
    GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);

    // Use the program object
    GLES20.glUseProgram(mProgramObject);

    // Load the vertex position
    mVertices.position(0);
    GLES20.glVertexAttribPointer ( mPositionLoc, 3, GLES20.GL_FLOAT, 
                                   false, 
                                   5 * 4, mVertices );
    // Load the texture coordinate
    mVertices.position(3);
    GLES20.glVertexAttribPointer ( mTexCoordLoc, 2, GLES20.GL_FLOAT,
                                   false, 
                                   5 * 4, 
                                   mVertices );

    GLES20.glEnableVertexAttribArray ( mPositionLoc );
    GLES20.glEnableVertexAttribArray ( mTexCoordLoc );

    // Bind the texture
    GLES20.glActiveTexture ( GLES20.GL_TEXTURE0 );
    GLES20.glBindTexture ( GLES20.GL_TEXTURE_2D, mTextureId );

    // Set the sampler texture unit to 0
    GLES20.glUniform1i ( mSamplerLoc, 0 );

    GLES20.glDrawElements ( GLES20.GL_TRIANGLES, 6, GLES20.GL_UNSIGNED_SHORT, mIndices );
}

现在我用位图尺寸设置视口（不工作）。我应该如何计算纹理的视口尺寸来适应屏幕保持比例？

谢谢你。

Answer 1

可能您应该使用ModelViewPrjoection矩阵。查看此源代码http://code.google.com/p/android-opengles-samples-for-vikulov-blogspot-com/source/browse/trunk/opengltemplate/src/com/vikulov/opengl/myglrenderer.java