android - OpenGL-es projection doesn't seem to work -

i've tried following lessons drawing shapes , applying projections them found here, projection doesn't seem work. far know i've copy-pasted pieces of code in project, here important code parts:

in renderer class:

@override public void ondrawframe(gl10 unused) {     gles20.glclear(gles20.gl_color_buffer_bit);      // set camera position (view matrix)     matrix.setlookatm(mvmatrix, 0, 0, 0, -3, 0f, 0f, 0f, 0f, 1.0f, 0.0f);      // calculate projection , view transformation     matrix.multiplymm(mmvpmatrix, 0, mprojmatrix, 0, mvmatrix, 0);      // draw shape     mtriangle.draw(mmvpmatrix); }  @override public void onsurfacechanged(gl10 unused, int width, int height) {     gles20.glviewport(0, 0, width, height);      float ratio = (float) width / height;     matrix.frustumm(mprojmatrix, 0, -ratio, ratio, -1, 1, 3, 7); } 

the draw method of triangle class:

public void draw(float[] mvpmatrix) {     gles20.gluseprogram(mprogram);      mpositionhandle = gles20.glgetattriblocation(mprogram, "vposition"); // handle vertex shader's vposition member     gles20.glenablevertexattribarray(mpositionhandle); // enable handle triangle vertices      gles20.glvertexattribpointer(mpositionhandle, coords_per_vertex, gles20.gl_float, false, vertexstride, vertexbuffer); // prepare triangle coordinate data      mcolorhandle = gles20.glgetuniformlocation(mprogram, "vcolor"); // handle fragment shader's vcolor member     gles20.gluniform4fv(mcolorhandle, 1, color, 0); // set color drawing triangle       mmvpmatrixhandle = gles20.glgetuniformlocation(mprogram, "umvpmatrix"); // handle shape's transformation matrix     gles20.gluniformmatrix4fv(mmvpmatrixhandle, 1, false, mvpmatrix, 0); // apply projection , view transformation      gles20.gldrawarrays(gles20.gl_triangles, 0, vertexcount); // draw triangle      gles20.gldisablevertexattribarray(mpositionhandle); // disable vertex array } 

the triangle still being stretched. doing wrong?

did try debug in onsurfacechanged? happens in lines? especially:

1. • what passed values width , height?
   • which value float ratio = (float) width / height; calculate?
   • do see changes values of mprojmatrix after call matrix.frustumm(mprojmatrix, 0, -ratio, ratio, -1, 1, 3, 7);?

2. how private final string fragmentshadercode in class triangle like? order of multiplication in line " gl_position = umvpmatrix * vposition;" + important.

your provided code looks quiet good, difficult issue here.