drawTexture method

void drawTexture({ required WebGLTexture? texture, required Buffer vertexBuffer, Float32List? matrix, })

Implementation

void drawTexture({required WebGLTexture? texture, required Buffer vertexBuffer, Float32List? matrix}) {
  _gl.checkError("drawTexture 01");

  final program = GlProgram(
    _gl,
    fragment_shader,
    vertex_shader
  ).program;

  _gl.useProgram(program);
  _gl.checkError("drawTexture 02");

  final _positionSlot = _gl.getAttribLocation(program, "Position");
  final _textureSlot = _gl.getAttribLocation(program, "TextureCoords");
  final _texture0Uniform = _gl.getUniformLocation(program, "Texture0");

  _gl.activeTexture(WebGL.TEXTURE10);
  _gl.bindTexture(WebGL.TEXTURE_2D, texture!);
  _gl.uniform1i(_texture0Uniform, 10);
  _gl.checkError("drawTexture 03");

  Float32List _matrix = Float32List.fromList([
    1.0, 0.0, 0.0, 0.0,
    0.0, 1.0, 0.0, 0.0,
    0.0, 0.0, 1.0, 0.0,
    0.0, 0.0, 0.0, 1.0
  ]);

  if(matrix != null) {
    _matrix = matrix;
  }

  final _matrixUniform = _gl.getUniformLocation(program, "matrix");
  _gl.uniformMatrix4fv(_matrixUniform, false, _matrix);

  _gl.checkError("drawTexture 04");
  _gl.bindBuffer(WebGL.ARRAY_BUFFER, vertexBuffer);

  _gl.checkError("drawTexture 05");

  final vao = _gl.createVertexArray();
  _gl.bindVertexArray(vao);

  _gl.vertexAttribPointer(_positionSlot.id, 3, WebGL.FLOAT, false, Float32List.bytesPerElement * 5, 0);
  _gl.checkError("drawTexture 06");

  _gl.enableVertexAttribArray(_positionSlot.id);
  _gl.checkError("drawTexture 07");

  _gl.vertexAttribPointer(_textureSlot.id, 2, WebGL.FLOAT, false, Float32List.bytesPerElement * 5, Float32List.bytesPerElement * 3);
  _gl.enableVertexAttribArray(_textureSlot.id);

  _gl.checkError("drawTexture 08");
  _gl.drawArrays(WebGL.TRIANGLE_STRIP, 0, 4);
  _gl.deleteVertexArray(vao);
  _gl.checkError("drawTexture 09");
  _gl.deleteProgram(program);
}