playn.core.gl.vertex-shader.txt Maven / Gradle / Ivy

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uniform vec2 u_ScreenSize;

attribute vec4 a_Matrix;
attribute vec2 a_Translation;
attribute vec2 a_Position;
attribute vec2 a_Texture;

varying vec2 v_TexCoord;

void main(void) {
  // Transform the vertex.
  mat3 transform = mat3(
    a_Matrix[0], a_Matrix[1], 0,
    a_Matrix[2], a_Matrix[3], 0,
    a_Translation[0], a_Translation[1], 1);
  gl_Position = vec4(transform * vec3(a_Position, 1.0), 1);

  // Scale from screen coordinates to [0, 2].
  gl_Position.x /= (u_ScreenSize.x / 2.0);
  gl_Position.y /= (u_ScreenSize.y / 2.0);

  // Offset to [-1, 1] and flip y axis to put origin at top-left.
  gl_Position.x -= 1.0;
  gl_Position.y = 1.0 - gl_Position.y;

  v_TexCoord = a_Texture;
}