Proper way to apply translation to vertices

Question

I have the simple vertex shader:

m44 op, va0, vc0 
mov v0, va1

and the fragment shader:

mov oc, v0

I pass this vertices to it:

  x     y   z  w  r  g  b
-0.3, -0.3, 0, 1, 1, 0, 0,
 0,    0.3, 0, 1, 0, 1, 0,
 0.3, -0.3, 0, 1, 0, 0, 1

The result triangle looks like I expected. Now I want to apply some translation to the result triangle. I have declared a matrix, call appendTranslation(0.2, 0, 0) and pass it to the vertex shader. The problem is that the triangle remained in the same position but with different vertices position. It looks like this:

Bad triangle

Why I got this result, and what is the proper way to apply translation to vertices?

Here is full code of my program:

package tests 
{
    import com.adobe.utils.AGALMiniAssembler;
    import flash.display.Sprite;
    import flash.display3D.Context3D;
    import flash.display3D.Context3DProgramType;
    import flash.display3D.Context3DRenderMode;
    import flash.display3D.Context3DVertexBufferFormat;
    import flash.display3D.IndexBuffer3D;
    import flash.display3D.Program3D;
    import flash.display3D.VertexBuffer3D;
    import flash.events.Event;
    import flash.geom.Matrix3D;
    import flash.utils.ByteArray;

    [swf(width="500", height="500")]
    public class Stage3dTest extends Sprite
    {
        private var _context:Context3D;
        private var _vertexBuffer:VertexBuffer3D;
        private var _indexBuffer:IndexBuffer3D;
        private var _program:Program3D;
        private var _mat:Matrix3D;

        public function Stage3dTest() {
            if (stage) {
                onAddedToStage();
            } else {
                addEventListener(Event.ADDED_TO_STAGE, onAddedToStage);
            }
        }
        private function onAddedToStage(event:Event = null):void {
            this.stage.stage3Ds[0].addEventListener(Event.CONTEXT3D_CREATE, onStage3dContext3DCreate);
            this.stage.stage3Ds[0].requestContext3D(Context3DRenderMode.SOFTWARE);
        }
        private function onStage3dContext3DCreate(event:Event):void {
            _mat = new Matrix3D();
            _mat.appendTranslation(0.2, 0, 0);
            _context = this.stage.stage3Ds[0].context3D;
            _context.configureBackBuffer(500, 500, 0, false);
            _vertexBuffer = _context.createVertexBuffer(3, 7);
            _indexBuffer = _context.createIndexBuffer(3);
            var p:Number = 0.3;
            var vertexData:Vector.<Number> = new <Number>[
                -p, -p, 0, 1, 1, 0, 0,
                0,   p, 0, 1, 0, 1, 0,
                p,  -p, 0, 1, 0, 0, 1
            ];
            _vertexBuffer.uploadFromVector(vertexData, 0, 3);
            _indexBuffer.uploadFromVector(new <uint>[0, 1, 2], 0, 3);
            createAndCompileProgram();
            addEventListener(Event.ENTER_FRAME, onEnterFrame);
        }
        private function createAndCompileProgram():void {
            _program = _context.createProgram();
            var assembler:AGALMiniAssembler = new AGALMiniAssembler();
            var code:String = "";
            code += "m44 op, va0, vc0\n"+
                    "mov v0, va1\n";
            var vertexShader:ByteArray = assembler.assemble(Context3DProgramType.VERTEX, code);
            code = "mov oc, v0\n";
            var fragmentShader:ByteArray = assembler.assemble(Context3DProgramType.FRAGMENT, code);
            _program.upload(vertexShader, fragmentShader);
        }
        private function onEnterFrame(event:Event):void {
            _context.clear(0.9, 0.9, 0.9, 1);
            _context.setProgram(_program);
            _context.setProgramConstantsFromMatrix(Context3DProgramType.VERTEX, 0, _mat);
            _context.setVertexBufferAt(0, _vertexBuffer, 0, Context3DVertexBufferFormat.FLOAT_4);
            _context.setVertexBufferAt(1, _vertexBuffer, 4, Context3DVertexBufferFormat.FLOAT_3);
            _context.drawTriangles(_indexBuffer);
            _context.present();
        }
    }
}

How / where did you call the appendTranslation()? Are you sure the final translated matrix is used in the Vertex Constants for your shader? Care to show the lines of code how you setup the translation to your Matrix? — chamberlainpi
just load different vertice and call present, that's how you translate them. If you want to do it with a matrix then load a new matrix and call present. Nothing is going to translate if you don't change the data and call present. — BotMaster
Thanks for your responses guys. I have updated my question, check it please. — patrick

nikitablack nikitablack · Accepted Answer · 2015-04-07T11:09:39

You need to transpose a matrix. You can do it manually or you can pass a parameter here:

_context.setProgramConstantsFromMatrix(Context3DProgramType.VERTEX, 0, _mat, true);

Proper way to apply translation to vertices

1 Answers