Taking the Development Ahead - Learn OpenGL ES: For Mobile Game and Graphics Development - page 245

to the uniform variable uM ( Listing 6-19 ) by calling the method

GLES20.glUniformMatrix4fv() .

Listing 6-18. TANK FENCE GAME 4/src/com/apress/android/tankfencegame4/
GLES20Renderer.java

private void renderEnemies(float[] enemiesMMatrix) {
GLES20.glUseProgram(_enemyProgram);
GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER,
_enemyBuffers[0]);
GLES20.glVertexAttribPointer(_enemyAPositionLocation,
3, GLES20.GL_FLOAT, false, 12, 0);
GLES20.glEnableVertexAttribArray(_enemyAPositionLocation);
GLES20.glUniformMatrix4fv(_enemiesUMLocation, 1,
false, enemiesMMatrix, 0);
GLES20.glUniformMatrix4fv(_enemiesUVPLocation, 1,
false, _enemiesVPMatrix, 0);
GLES20.glBindBuffer(GLES20.GL_ELEMENT_ARRAY_BUFFER,
_enemyBuffers[1]);
GLES20.glDrawElements(GLES20.GL_TRIANGLES, 24,
GLES20.GL_UNSIGNED_SHORT, 0);
}

Finally, to transform the vertex positions this matrix is combined with the view-pro-
jection matrix, as shown in Listing 6-19 . Please note that the _enemiesVPMatrix
( Listing 6-18 ) contains a copy of the elements from _planeVPMatrix :

Matrix.multiplyMM(_planeVPMatrix, 0,
_ProjectionMatrix, 0, _ViewMatrix, 0);
System.arraycopy(_planeVPMatrix, 0, _enemiesVPMatrix,
0, 16);

Listing 6-19. TANK FENCE GAME 4/src/com/apress/android/tankfencegame4/
GLES20Renderer.java