perspectiveFromFieldOfView function
Generates a perspective projection matrix with the given field of view. This is primarily useful for generating projection matrices to be used with the still experiemental WebVR API.
@param {mat4} out mat4 frustum matrix will be written into @param {Object} fov Object containing the following values: upDegrees, downDegrees, leftDegrees, rightDegrees @param {number} near Near bound of the frustum @param {number} far Far bound of the frustum @returns {mat4} out
Implementation
List<double> perspectiveFromFieldOfView(List<double> out, fov, near, far) {
final upTan = math.tan((fov.upDegrees * math.pi) / 180.0);
final downTan = math.tan((fov.downDegrees * math.pi) / 180.0);
final leftTan = math.tan((fov.leftDegrees * math.pi) / 180.0);
final rightTan = math.tan((fov.rightDegrees * math.pi) / 180.0);
final xScale = 2.0 / (leftTan + rightTan);
final yScale = 2.0 / (upTan + downTan);
out[0] = xScale;
out[1] = 0.0;
out[2] = 0.0;
out[3] = 0.0;
out[4] = 0.0;
out[5] = yScale;
out[6] = 0.0;
out[7] = 0.0;
out[8] = -((leftTan - rightTan) * xScale * 0.5);
out[9] = (upTan - downTan) * yScale * 0.5;
out[10] = far / (near - far);
out[11] = -1.0;
out[12] = 0.0;
out[13] = 0.0;
out[14] = (far * near) / (near - far);
out[15] = 0.0;
return out;
}