Update: The previous statement is incorrect, according to comment by user infact.įurthermore, I have found this tidbit in the ES 2.0 spec, but do not understand what it means:

My code includes some simple Model/View/Projection matrix math, but none of it currently influences my texture coordinate values. I have come to understand that I need to perform 'perspective correction,' presumably in my vertex and/or fragment shaders, but I am unclear how to do this. It's being drawn completely facing the screen, and is not being tilted (i.e. The trapezoid is being drawn using GL_TRIANGLE_STRIP in OpenGL ES 2.0 (on an iPhone). (Note: the last image is not intended to be a 100% faithful representation, but it should get the point across.) This illustration demonstrates the issue: Instead of appearing as a single unbroken quadrilateral, a discontinuity occurs at the diagonal line where its two comprising triangles meet. GLES20.I have drawn a textured trapezoid, however the result does not appear as I had intended. GLES20.glAttachShader(mProgram, fragmentShader) // add the fragment shader to program GLES20.glAttachShader(mProgram, vertexShader) // add the vertex shader to program MProgram = GLES20.glCreateProgram() // create empty OpenGL ES Program Int fragmentShader = loadShader(GLES20.GL_FRAGMENT_SHADER, fragmentShaderCode)

Int vertexShader = loadShader(GLES20.GL_VERTEX_SHADER, vertexShaderCode) initialize byte buffer for the draw listīyteBuffer dlb = ByteBuffer.allocateDirect(drawOrder.length * 2) // (# of coordinate values * 2 bytes per short) initialize vertex byte buffer for shape coordinatesīyteBuffer bb = ByteBuffer.allocateDirect(squareCoords.length * 4) // (# of coordinate values * 4 bytes per float) Static final int vertexStride = COORDS_PER_VERTEX * 4

Private final String fragmentShaderCode = number of coordinates per vertex in this array I've tried several values for vertexCount (1 thru 12), and none work. The Renderer class simply creates an instance of this shape and calls the draw method.įor some reason, the tutorial does not give the values/declaration for vertexStride and vertexCount, so the ones I have in there are educated guesses. I've included the code that I'm using to define and draw the shape, which is copied almost exactly from the tutorial. So I've been going through the official OpenGL ES 2 tutorials for Android, and I've gotten to the part that involves drawing shapes, but I can't seem to get a square to work.

Hello triangle in opengl es 2.0 example